From Mohamed Fadel Fahmy, For CNN

December 19, 2011

A protester holds up a bullet casing after deadly clashes with the military in Tahrir Sqaure

Cairo (CNN) -- Police and military troops clashed Monday with protesters in Egypt's Tahrir Square, the symbolic center of the uprising that brought down President Hosni Mubarak earlier this year.

At least two protesters were killed, according to field doctor Ahmed Khalil, bringing the total number of dead in protests to 13 since Friday.

Monday was the fourth day that pro-democracy demonstrators battled Egyptian security, their anger stoked by images of a military police officer stomping on a woman's exposed stomach over the weekend.

A top general on the military council that runs Egypt blamed the violence on protesters, saying they had provoked the clashes.

Demonstrators have been using "very destructive methods," including Molotov cocktails, gas bombs and rocks, said Gen. Adel Amara of the Supreme Council of the Armed Forces (SCAF) on Monday.

"Protests start peacefully then they turn into attacks on government buildings," Amara said, saying "events have proven there is a plan to destroy the country."

He vowed that the generals honestly intend to hand power to a civilian government -- a key demand of the thousands who have been demonstrating.

Gigi Ibrahim, a prominent activist who was present at the clashes early on Monday, accused the army and police of firing "indiscriminately."

"They stormed into the square destroying cars, shops and even the field clinic and they will blame it on protesters," she said.

Control of the square has gone back and forth between the protesters and security forces, who have fired live ammunition, bird shot and tear gas.

"Dozens of detainees arrested during the clashes have suffered serious injuries that need medical attention," said Ragia Omran, a lawyer who volunteers to assist detained protesters, who said some prosecutors were allowing wounded to be transferred to hospitals and some were not.

But Maj. Mohamed Askar of SCAF said protesters were capturing and wounding soldiers.

"The army soldiers they kidnapped and returned are now in the hospitals. The rebels also captured three officers, tortured them and released them. They were even talking about a prisoner swap," he said.

CNN could not independently confirm the details of either side's account.

Newly elected lawmakers, intellectuals, and prominent clerics have been at the scene to try to reach a truce but their efforts have not succeeded.

Cairo's stock exchange plunged Sunday amid the new turmoil, while Saturday's images of the woman's beating appeared to draw more people to the streets.

The woman who was seen in police custody with her top removed was set upon, along with a male companion, by more than 20 police officers during Saturday's demonstrations in Cairo.

She had been dressed in a traditional robe and headscarf -- but as police clubbed her and dragged her down the street, those items were pulled away, exposing her midriff and blue brassiere in a country known for its Islamic conservatism.

Then one of the police officers aimed a foot at her upper abdomen and stamped squarely on it, while another officer jumped on the man as he lay on the pavement nearby.

"The army were like vultures who found a prey," said Mohamed Zeidan, who filmed the beating from a balcony overlooking Tahrir Square. He said after he stopped filming the beating out of fear of being discovered, "The soldiers even beat an older couple who tried to help her up."

Images of the woman's treatment were splashed across the front pages of Egyptian newspapers on Sunday and zipped around the world on social media networks. But a spokesman for the military, which has ruled Egypt since February's ouster of longtime autocrat Hosni Mubarak, had no apologies.

"What was woman like her doing in a conflict zone?" asked the spokesman, Maj. Mohamed Askar. "She must have participated in the attacks on the military and the Cabinet."

Askar questioned why the woman has not come forward to identify herself.

"Our troops do not just attack people for no reason," he said. "If she had nothing to hide then she would have presented herself. Where is she?"

Two people who know her, including the man seen being beaten alongside her in the video, said the woman is a political activist and student. She does not want to speak to reporters now, but a journalist who saw the incident and was beaten as well said the woman suffered "serious bruises and cuts" as a result.

U.S. Secretary of State Hillary Clinton condemned the reports of violence on Sunday and said her thoughts are with the families of those killed or injured.

Tahrir Square has been the epicenter of anti-government demonstrations since last January, when the revolt against Mubarak began. Fresh protests sprouted in November, when the generals named Mubarak-era premier Kamal Ganzouri as a caretaker prime minister until parliamentary elections are complete.

CNN's Ben Wedeman contributed to this report.