An angry mob attacked a group of mainly Christian protesters demanding drastic measures to heal religious tension amid a spike in violence, leaving 65 people injured, officials said.
The Christian protesters have been holding their sit-in outside the state television building in Cairo for nearly a week following deadly Christian-Muslim clashes that left a church burned and 15 people dead.
More than 100 people rushed into the sit-in area on Sunday, lobbing rocks and fire bombs from an overpass and charging toward the few hundred protesters sleeping in the area. Vehicles were set on fire and fires burned in the middle of the street.
Police and army troops fired in the air to disperse the crowd, and a tree was set on fire under the overpass.
The security official, who spoke on condition of anonymity because he was not authorised to speak to the media, said the attackers had returned to avenge an earlier scuffle with the protesters who prevented a motorist from going through the area. A fight ensued, and the motorists fired blank rounds. The protesters chased the motorist and beat him badly.
Marc Mino, a protest organiser, told state TV the motorists had provoked the fight after refusing to be searched before entering the protest area, then provoking the protesters.
Medics said 65 were injured in Sunday's melee, two in critical condition. The security official said nearly 50 of the riot instigators were arrested.
A witness, Alfred Raouf, said armoured vehicles later blocked traffic and pedestrians from going down from the bridge toward the protest area. The number of protesters at the sit-in shrunk, but those remaining insisted the strike would continue as their area was cordoned off by the security, Raouf said.
Religious clashes and a rising wave of crime have proved to be a major challenge for Egypt's military rulers in the days following the 18-day uprising that led to the Feb. 11 ouster of ex-President Hosni Mubarak.
Following the religious violence, the military vowed to respond firmly to instigators of violence and promised to respond to a number of the Christian demands, including reopening nearly 50 churches. But no trial date has been set for those responsible for the church burning or the violence last week.
Just hours before the Cairo violence, several suspected Islamic extremists bombed the tomb of a Muslim saint in the northern Sinai town of Sheik Zweid, said a security official, also declining to be identified because he wasn't authorized to release the information. The official said the eight or nine attackers fled the area. Muslim radicals have blown up at least five other Muslim shrines, because they believe the veneration of saints as a violation of Islam.
Meanwhile, doctors said Egypt's ex-first lady Suzanne Mubarak was in stable condition after treatment for a "panic attack" and has effectively been put under arrest in the hospital in the Red Sea resort of Sharm el-Sheikh pending further investigation of corruption allegations, officials said Saturday.
Mrs. Mubarak fainted and suffered chest pains following a three-hour interrogation Friday which ended with a decision to detain her for 15 days as prosecutors looked at the sources of her wealth. She has been accused of taking advantage of his position for personal gain.
Health Minister Ashraf Hatem said the 70-year old Mrs. Mubarak was in stable condition Saturday after a 24-hour monitoring period in the intensive care unit of the hospital in the Red Sea town of Sharm el-Sheikh. She is in the custody of the police, Hatem said, according to Egypt's state news agency MENA.
Later, a second team recommended she remain under observation for an additional 48 hours, according to the hospital's director, Dr. Mohammed Fatahallah. He said the team determined that Mrs. Mubarak still has high blood pressure and suffers from chest pains, and an angioplasty may be necessary. He was speaking to The Associated Press.
The continuing treatment makes it unlikely she will be transferred quickly to a Cairo women's prison facility, where she had been expected to be moved.
Earlier, a hospital official had told The Associated Press that Mrs. Mubarak on Friday "suffered from a sudden panic attack after hearing that she will be sent to prison." The hospital official spoke on condition of anonymity because he is not allowed to release the information before further tests were conducted.
Mrs. Mubarak's 83-year-old husband also is being treated in the Sharm el-Sheikh hospital, for a heart condition.
The former president had been questioned several times about allegations that he illegally amassed vast wealth, but Mrs. Mubarak was interrogated on Thursday for the first time on corruption charges.
The Mubaraks and other members of the former regime have been the subject of legal efforts to bring them to trial since the ex-president was forced to resign Feb. 11.
The process has been complicated by slow procedures and- in the Mubaraks' case- by health issues. Many in the protest movement have been critical of the current military rulers for being slow in pursuing corrupt officials, although many former regime members have been jailed.