Pro-Mohammed Morsi protesters, army-backed demonstrators clash in Egypt

Updated at 1:53 p.m. ET

(CBS News) Dozens of people died early Saturday in Egypt after huge street protests pitted supporters of ousted Islamic President Mohammed Morsi against demonstrators backed by the Egyptian army.

CBS News' Clarissa Ward reports from Cairo that two different versions of events were being told by the different sides involved in the clashes.

The Interior Ministry said that 20 people were killed when police tried to disperse a group of pro-Morsi supporters who were trying to block a bridge. The Muslim Brotherhood claims that at least 129 people were killed. Later, the Health Ministry announced that at least 65 had died in the clashes.

A man who witnessed the clashes told CBS News they began at around 3 a.m. and peaked at 6 a.m. He said that the military, police and what he referred to as "civilian thugs" opened fire on the pro-Morsi march that was heading toward Raba'a.

Ward and her CBS News crew saw at least 39 dead bodies at a makeshift morgue at the Raba'a al Adawiya mosque in Cairo, where Morsi's supporters have been camped out since he was ousted at the beginning of the month.

Ward reports 37 of those killed were Muslim Brotherhood supporters and two were some of the "thugs" to whom the eyewitness referred.

The dead were being carried out of the morgue one by one to be taken to hospitals, given a death certificate and buried.

There was blood everywhere in the morgue, Ward reports. Volunteers tried futilely to mop it up with rags, only smearing it across the floor. Relatives sobbed over their loved ones. Women shrieked. The crowd outside chanted "down with the military regime." The stench of blood and the heat of the people was overwhelming.

Ward spoke to the head doctor in charge of the field hospital, who said that the dead and wounded started pouring in just after 3 a.m. He told CBS News that almost all had gunshot wounds to the head, neck and heart.

The doctor said that he did not have the right equipment to treat them or enough blood to save them. A couple of hours into the clashes, the field clinic was overwhelmed and stopped taking patients. The doctor's eyes were dazed with fatigue and shock as he spoke.