An protester throws a tear gas canister back toward riot police in Tahrir Square on Sunday, January 27, in Cairo, Egypt. An judge sentenced 21 people to death Saturday for their roles in a football game riot last year, a ruling that sparked deadly clashes between security forces and relatives of the convicted.
Egyptian policemen and relatives on January 27 gather upon the arrival of the coffins of their colleagues killed in the violence one day earlier in Cairo.
A protester throws a rock toward opposing demonstrators on January 27 in Cairo.
Egyptian protesters throw stones toward riot police on January 27 in Tahrir Square.
An Egyptian protester runs with a live tear gas canister toward Egyptian riot police on Saturday, January 26, in Cairo.
Egyptian fans of Al-Ahly football club celebrate outside the club's headquarters in Cairo on January 26.
Egyptian fans of Al-Ahly football club celebrate outside the club's headquarters in Cairo on January 26.
Egyptian protesters stand by the burning door of a school building on January 26, in Cairo.
An Egyptian protester carries an injured boy away from clashes with Egyptian riot police on January 26, in Cairo.
Egyptians climb over a fence at the Al-Ahly home stadium on January 26 in Cairo.
An Egyptian fan of Al-Ahly football club fires celebratory shots in the air and lights a flare as club supporters celebrate outside its headquarters in Cairo on January 26.
A protester throws a rock at riot police on January 26, in Cairo.
A fan of Al-Ahly football club lights a flare as club supporters celebrate on January 26 in Cairo.
Al-Ahly football club supporters celebrate outside the club's headquarters in Cairo on January 26.
Al-Ahly football club supporters celebrate on January 26.
Smoke billows from a burning vehicle set on fire by Egyptian protesters outside the Port Said prison on January 26.
Egyptians react after the sentencing in Port Said on January 26.
An Al-Ahly soccer fan swings a live flare above his head on January 26 in Cairo.
An Egyptian protester tries to carry an injured man away from clashes with riot police on January 26, in Cairo.
Egyptian fans of Al-Ahly football club rally outside the club's headquarters in Cairo on January 26.
An Egyptian protester runs away from a cloud of tear gas fired by Egyptian riot police on January 26, in Cairo.
Relatives of victims killed during the 2012 Port Said soccer game react after the verdict of the court, at a courthouse in Cairo, on January 26.
Relatives and friends of Egyptian protesters who were killed in Suez during clashes with riot police Friday, load a body onto an ambulance outside the morgue in Suez on January 26.
A fan of Al-Ahly football club lights a flare as club supporters celebrate outside its headquarters in Cairo on January 26.
Two protesters stand on top of a piece of furniture while riot police watch from a nearby rooftop in Cairo.
A protester throws a rock at riot police in Cairo.
An Egyptian protester walks through a cloud of tear gas fired by Egyptian riot police.
An "Ahly-Ultra" soccer fan holds a smoke flare above his head in Cairo.
A protester walks through a damaged school building.
A protester removes the net from a basketball goal in a Cairo schoolyard.
Protesters and football fans clash with riot police near Egypt's interior ministry.
Protesters and fans of Al-Masry football club take part in a demonstration in front of the prison in Port Said.
Egyptian protesters and fans of Al-Masry football club wave their club colors as they take part in a demonstration in front of the prison in the Egyptian Suez Canal city of Port Said on Friday, January 25, calling for the prisoners who are suspected of killing 74 fans of Al-Ahly club during a football match in February 2012 not to be transferred to Cairo to attend their trial. A judge sentenced 21 people to death for their roles in the riot last year.
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
Clashes in Egypt after court sentencing
STORY HIGHLIGHTS
- Protests on the two-year anniversary of the revolution left seven people dead Friday
- Chaos erupted after 21 people were sentenced to death after a football riot in Port Said
- Critics have accused Morsy of becoming a new dictator
- Morsy announces a temporary curfew in three places and a meeting among different parties
(CNN) -- Two years ago, Egyptians toppled a longtime dictator and reveled in the hope of a new future. But frustration over the new leadership and controversial court verdicts have ignited clashes regularly.
Here's what's behind the most recent unrest, which flared up on the two-year anniversary of the revolution.
What sparked this latest rash of violence?
Two seemingly unrelated developments.
Read: Egypt's Morsy declares curfew in 3 cities
Friday was the two-year anniversary of the 2011 Egyptian revolution. Protesters who have been angry with the slow pace of change and with some of the steps President Mohamed Morsy has taken clashed with his supporters and police in the cities such as Suez and Ismailia.
Violence sparked by Egypt verdict
Egypt's Morsy imposes curfew after riots
New, deadly violence in Egypt
Tensions high in Port Said, Egypt
Egypt's football fans demand justice
At least seven people were killed in those clashes, including several by gunfire. It was not immediately clear who was responsible.
Then on Saturday, a judge issued death sentences for 21 people from Port Said for their roles in a football game riot last year.
The court rulings sparked deadly clashes between security forces and relatives of the convicted. Over the course of two days, at least 38 people -- including civilians and soldiers -- were killed in Port Said. `
Dubbed the "massacre at Port Said" by Egyptian media, the riot broke out on February 1, 2012, after Port Said-based Al-Masry defeated Cairo's Al-Ahly, 3-1. The riot left 74 people dead and 1,000 injured.
Fans from both sides bashed each other with rocks and chairs. It was unclear whether intense sports rivalries or political strife sparked the melee.
What's the back story of tensions between Port Said and Cairo?
Port Said residents say they have grievances that date back six decades.
Over the past 60 years, residents of Port Said have felt betrayed by Egyptian security forces during a series of wars with Israel.
Thousands of residents were displaced several times because of the Suez War, the Six-Day War of 1967, the War of Attrition with Israel, and the 1973 Arab-Israeli War.
Residents of Port Said, in northeastern Egypt, believed security forces did not adequately defend their city.
In addition, some say Cairo has not invested enough in Port Said's infrastructure, and that their city doesn't reap enough tax benefits from trade with international ships that pass though Port Said via the critical Suez Canal.
Some also say Port Said is still getting the cold shoulder from Cairo after a 1999 assassination attempt of then-President Hosni Mubarak, who was visiting the city.
Why are some Egyptians angry with Morsy?
Morsy, Egypt's first democratically elected president, came to power last June following Mubarak's ouster a year earlier.
But accusations of power hoarding soon followed.
Morsy issued a sweeping presidential decree in November, which prevented any court from overturning his decisions until a new, post-Mubarak constitution was passed. The ruling essentially gave him unchecked power, protecting from judicial review any decisions he has made since assuming office.
Protesters decried the "birth of a new pharaoh" and "Morsy the dictator."
But Morsy defended his move, saying it was only temporary until a new constitution is put in place. He said it was intended to safeguard the revolution, in part by preventing courts from interfering with the work of Egypt's Constituent Assembly, the body charged with drafting a new constitution.
The judges, many of whom were holdover loyalists from the government of Mubarak, are widely viewed as hostile to the Islamists who now dominate the assembly that has been charged with framing a new constitution.
The constitution eventually passed with a nearly two-thirds majority.
What happens now?
During a speech Sunday night, Morsy declared a limited state of emergency for violent hot spots and announced a 30-day nighttime curfew for the provinces of Port Said, Ismailia and Suez.
Morsy said some protesters' violent behavior "does not have anything to do with the Egyptian revolution. ... In fact, it is against the revolution."
But he acknowledged the legitimate dissent in Egypt, saying "dialogue is the only way to bring about stability and security."
To this end, he invited representatives from 11 political parties to a meeting Monday.
The meeting "is meant to address problems in Egypt, as opposed to express anger," Morsy's spokesman told state-run TV.
But for a country that has seen rounds of change, dissent, celebration and violence, it's unclear what the next chapter will be.
CNN's Reza Sayah and Tim Hume contributed to this report.