CAIRO -- Security forces clashed with supporters of Egypt's ousted President Mohammed Morsi early Saturday, killing at least 38 protesters, the Health Ministry said, in an outburst of violence that put the possibility of political reconciliation in the deeply divided nation ever further out of reach.
In chaotic scenes, pools of blood stained the floor and bodies were lined up under white sheets in a makeshift hospital near the site of the battles in eastern Cairo as doctors struggled to cope with the flood of dozens of wounded.
The extent of the carnage underlined the willingness of police to unleash deadly firepower against any expansion of Islamist-led protests demanding the reinstatement of Morsi. Military-backed authorities are feeling emboldened after millions turned out for nationwide rallies Friday called by the army chief in support of a tough hand against what he called "terrorism."
The bloodshed also pointed to the Islamists' readiness to challenge the security forces as Morsi's supporters try to win over public support for their cause.
The fighting, which began before dawn and stretched out over several hours, was one of the deadliest bouts of violence since the military ousted Morsi on July 3 in the wake of massive protests demanding his removal. Soon after Morsi's fall, more than 50 of his supporters were killed in a similar outbreak of violence outside a headquarters of the Republican Guard.
A leading figure of Morsi's Muslim Brotherhood, Mohammed el-Beltagy, blamed the violence on army chief Gen. Abdel-Fattah el-Sissi's call for rallies on Friday.
"This is the mandate el-Sissi took last night -- to commit massacres and bloodshed against peaceful protesters denouncing the military coup," el-Beltagy said in a statement on his Facebook page.
The clashes began after a crowd of Morsi supporters late Friday moved out of their main sit-in camp where they have been located for nearly three weeks, in front of the Rabaah al-Adawiyah Mosque.
Some of them installed themselves on a nearby major boulevard, blocking traffic. They began to set up tents there, planning to stay there at least three days, said Mahmoud Zaqzouq, a Brotherhood spokesman. Others went up on a nearby highway overpass, he told The Associated Press.
Police moved in and fired tear gas to break up the crowds at around 2 a.m., and protesters responded with volleys of stones in battles near a memorial to former President Anwar Sadat, who was assassinated in 1981.
Gunshots also rang out, seemingly from both sides, said one witness, Mosa'ab Elshamy, a freelance photographer, though he could not tell who started firing.
Armed residents of the area also joined the police side, and there were also plainclothes police carrying handguns, he said. The security forces "felt a bit more unrestrained than other times," said Elshamy, who has extensively covered other clashes with police the past two years. "It was clear they had no restraints."
Ragab Nayel Ali, one of the pro-Morsi protesters, said security forces fired first with tear gas and birdshot. "Protesters replied by hurling rocks and started building walls," said Ali, who was injured in an accident as he ferried wounded on his motorcycle from the fighting to a field hospital.
At the makeshift clinic set up at the Rabaah al-Adawiya encampment, men shouted "God is great," and women wailed as bodies were loaded into ambulances to be taken for examination at hospitals. Bodies of more than a dozen men lay on the blood-splattered floor with white sheets over them.
"They aimed at killing the people. They aimed the head and the neck," said Ahmed Abdullah, a doctor at the field clinic, as he wiped tears from his eyes.
By the early afternoon, Health Ministry spokesman Khaled el-Khateeb said that 38 people were killed, and another 239 people wounded in the violence.
A medical official at a nearby hospital that received 23 bodies told The Associated Press that many of those killed had bullet wounds at chest level or higher. He spoke on condition of anonymity because he was not authorized to talk to the press.
The Interior Ministry, which oversees the police force, said in a statement that residents in the district began clashing with the pro-Morsi marchers when their protest blocked a major artery. The ministry said police who intervened were trying to break up the two sides by firing tear gas.
Amr Moussa, a former Arab League chief and presidential candidate who lost to Morsi last year, called on the government to make clear what happened.
"Yesterday masses went out to the streets against terrorism, violence and bloodshed. Do not forget that," the secular-leaning Moussa said in a statement.
Interior Ministry spokesman Maj. Gen. Hani Abdel-Latif said 14 policemen and 37 army troops were wounded in the violence. He said that two of the policemen had gunshot wounds to the head. He claimed that the police only used tear gas against the protesters.
He warned against "following calls for non-peaceful protests."
It was not clear how troops could have been wounded in the fighting, since the army did not appear to be involved in the fighting. Elshamy said troops' only involvement he saw was that some fired into the air at one point, causing both police and protesters to back up for a short time.
Interim President Adly Mansour told the private TV station al-Hayat that his government seeks to include everyone, but it will not accept lawlessness, blocked roads and attacks on state institutions.
"I can't negotiate with anyone who has committed a crime. But those who were duped or those who want to belong to Egyptian society, we welcome them," he said. But he added: "The state must interfere (against lawlessness) firmly."
The violence is certain to only further deepen the divides over the military coup that ended Morsi's one year in office. Millions joined four days of protests that began June 30 demanding Morsi be removed, accusing him of empowering his Brotherhood and failing to resolve the country's problems.
Many of Morsi's opponents, including liberals, leftists and moderate Muslim, secular and Christian Egyptians, have now enthusiastically embraced the military after el-Sissi's removal of Morsi. The military-backed interim leadership has pushed a fast-track transition plan to return to a democratically elected government by early next year.
Morsi's supporters, meanwhile, reject the new political order, and say the military illegally ousted the country's first democratically elected leader. They have kept up their sit-in and held near daily rallies elsewhere in the capital to demand Morsi be reinstated.
While the main sit-in has been peaceful, protests elsewhere have repeatedly turned violent, and some 180 people have been killed in clashes nationwide. Each side has accused the other of sparking clashes.
El-Sissi called for Friday's mass rallies to give the military a mandate to fight "violence and terrorism," raising speculation that he may be planning a crackdown against the pro-Morsi rallies.
Giant crowds responded to his call Friday, packing main squares in cities around the country, voicing support for a tough hand against Islamists. Morsi supporters also held large rallies Friday, although smaller than those of the pro-military camp.
The rival demonstrations erupted into violence in the Mediterranean coastal city of Alexandria that left eight dead.
More than 100 Morsi supporters had taken refuge in a central mosque in Alexandria, and held 17 of their rivals hostage overnight inside to try and fend off a security siege of the building. A security official said the hostages were freed and those inside the mosque arrested. The official spoke on condition of anonymity because he was not authorized to speak to the media
Also on Friday, authorities announced that Morsi was formally placed under investigation on a host of allegations including murder and conspiracy with the Palestinian militant group Hamas. Morsi has been held incommunicado since being taken into military custody on July 3.
Associated Press writers Aya Batrawy and Mariam Rizk contributed to this report.