PORT SAID, Egypt (AP) -- Tens of thousands of mourners poured into the streets of the restive Egyptian city of Port Said on Sunday for a mass funeral for most of the 37 people killed in rioting a day earlier, chanting slogans against Islamist President Mohammed Morsi.
Violence erupted briefly when some in the crowd fired guns and police responded with volleys of tear gas, witnesses said. State television reported 110 were injured.
"We are very worried about what may happen after the burial," said local youth activist Rasha Hamouda, noting the city was fraught with tension.
The violence in the city, about 140 miles northeast of Cairo, broke out on Saturday after a court on Saturday convicted and sentenced 21 defendants to death for their roles in a mass soccer riot in a Port Said stadium on Feb. 1, 2012 that left 74 people dead. Most of those sentenced to death were local soccer fans from Port Said. The 21 were convicted on murder charges and the court is to rule on the remainder of the 73 defendants in March.
The riots stemmed mostly from animosity between police and die-hard Egyptian soccer fans, known as Ultras, who have become highly politicized. The Ultras frequently confront police and were also part of the uprising that toppled Hosni Mubarak's regime two years ago.
They were also at the forefront of protests against the military rulers who took over from Mubarak and are now again on the front lines of protests against the Morsi, the country's first freely elected leader.
A prominent Islamist leader delivered a thinly veiled warning that Islamist groups would set up militia-like vigilante groups to protect public and state property against attacks.
Addressing a news conference, Tareq el-Zomr of the once-jihadist Gamaa Islamiya, said:
"If Security forces don't achieve security, it will be the right of the Egyptian people and we at the forefront to set up popular committees to protect private and public property and counter the aggression on innocent citizens."
The threat by el-Zomr was accompanied by his charge that the mostly secular and liberal opposition was responsible for the deadly violence of the past few days, setting the stage for possible bloody clashes between protesters and Islamist militiamen. The opposition denies the charge.
There was also a funeral in Cairo for two policemen killed in the Port Said violence a day earlier. Several policemen grieving for their colleagues heckled Interior Minister Mohammed Ibrahim, who is in charge of the force, when he arrived for their funeral, according to witnesses. The angry officers screamed at the minister that he was only at the funeral for the TV cameras -- a highly unusual show of dissent in Egypt, where the police force maintains military-like discipline.
Ibrahim hurriedly left and the funeral proceeded without him.
In Port Said, mourners chanted "There is no God but Allah," and "Morsi is God's enemy" as the funeral procession made its way through the city after prayers for the dead at the city's Mariam Mosque. Women clad in black led the chants, which were quickly picked up by the rest of the mourners.
There were no police or army troops in sight. But the funeral procession briefly halted after gunfire rang out. Security officials said the gunfire came from several mourners who opened fire at the Police Club next to the cemetery.
A witness said the police responded to the gunfire with volleys of tear gas. The witness and the officials spoke on condition of anonymity because of the sensitivity of the situation in the city on the Mediterranean at the northern tip of the Suez Canal.
Survivors and witnesses of the Port Said soccer melee blame Mubarak loyalists for the violence, saying they had a hand in instigating the killings. The troubles erupted after Port Said's home team Al-Masry beat Cairo's Al-Ahly 3-1. Some witnesses said "hired thugs" wearing green T-shirts and posing as Al-Masry fans led the attacks.
Other witnesses said at the very least, police were responsible for gross negligence in the soccer violence, which killed 74 people, most of them Al-Ahly fans.
Anger at police was evident in Port Said, home to most of the 73 men accused of involvement in the bloodshed.
The trial was in Cairo and Judge Sobhi Abdel-Maguid did not give his reasoning when he handed down the guilty verdicts and sentences for 21 defendants. Executions in Egypt are usually carried out by hanging.
Verdicts for the remaining 52 defendants, including nine security officials, are to be delivered on March 9. Some have been charged with murder and others with assisting the attackers. All the defendants -- who were not present in the courtroom Saturday for security reasons -- can appeal the verdict.
In Port Said on Sunday, army troops backed by armored vehicles staked out positions at key government facilities to protect state interests and try to restore order.
The military issued a statement urging Port Said residents to exercise restraint and protect public property, but also warning that troops would deal "firmly" with anyone who "terrorizes" citizens or infringes upon the nation's security and stability.
Rioters on Saturday attacked the prison where the defendants were being held and tried to storm police stations and government offices around the city. Health officials say at least 37 people were killed, including two policemen, in rioting on Saturday.
The clashes in Port Said were the latest in a bout of unrest across the country that has left a total of 48 people dead since Friday. That death toll includes 11 people killed in clashes between police and protesters marking the second anniversary of the uprising that overthrew Mubarak after nearly 30 years of authoritarian rule.
Clashes broke out in Cairo for the fourth straight day on Sunday, with protesters and police near central Tahrir Square, birthplace of the 2011 uprising. Police fired tear gas while protesters pelted them with rocks.
The clashes show how turmoil was deepening in Egypt nearly seven months after Morsi took office. Critics say Morsi has failed to carry out promised reforms of the judiciary and police, and claim little has improved in the two years since the uprising.
At the heart of the rising opposition toward Morsi's government is a newly adopted constitution, which was ratified in a nationwide referendum.
Opponents claim the document has an Islamist slant. It was drafted hurriedly by the president's allies without the participation of representatives of liberals and minority Christians on the panel that wrote the charter.
Protesters on the streets this past week demanded the formation of a national unity government, early presidential elections and amendments to disputed clauses in the constitution.
Morsi and the Muslim Brotherhood, the Islamist group from which he hails, counter that the opposition was seeking to overturn the results of democratic and free elections. The Brotherhood, a well-organized and established political group in Egypt for decades, has emerged as by far the most powerful force in post-Mubarak Egypt.
As the situation in Port Said spiraled out of control Saturday, police disappeared from the city's streets, residents and security officials said, staying put in their camps, police stations and the city's security headquarters.
The military then dispatched troops to the city, taking up positions at vital state facilities, including the local power and water stations, the city's main courthouse, the local government building and the city prison. Navy sailors were guarding the local offices of the Suez Canal company.
Navy vessels were escorting merchant ships sailing through the international waterway, a vital income earner for Egypt's beleaguered economy. Military helicopters were flying over the canal to ensure the safety of shipping, according to Suez Canal spokesman Tareq Hassanein.
Residents said Port Said was quiet overnight except for intermittent bursts of gunfire. The city was still on edge early Sunday -- but streets were largely deserted, stores were closed for the second successive day, and some hotels asked guests to leave, fearing more violence.