BEIJING, July 9 (Xinhuanet) -- ’s interim leader has expressed sorrow over the deaths of at least 51 supporters of ousted president Mohamed , including women and children, near the headquarters of the country’s Republican Guard. Hundreds of others were injured. An official investigation has now been launched into the worst day of killings since activists took to the streets in 2011.

Supporters of ousted Egyptian president Mohamed Morsi claim the army launched a surprise attack before dawn.

"We were praying and the security forces attacked us with live ammunition and tear gas bombs," said injured Morsi supporter Mahmoud Hussein.

Egyptian soldiers at the scene tell a different story. "We were there to ensure the safety of the people. When we were there, they started firing at us and throwing Molotov cocktails and bricks. Many of my colleagues were hit by the fire and the proof is here at the hospital," soldier Mohamad Ibraheem said.

At the site of killing supporters of deposed President Morsi are continuing to regroup. These are activists just arriving from the Sinai area.

This has been the worst day of violence in Egypt since the troubles began. Morsi supporters say they are here to stay.

"We won’t leave this place until we achieve our aims," said a supporter named Ahmed.

Egypt’s interim president has ordered an investigation into the deaths and called for calm. The violence appears to have derailed attempts to forge a desperately needed interim government.

The hardline el Nour Party that had supported Mr Morsi’s removal withdrew from talks to choose an interim prime minister, describing the shooting incident as a "massacre". Massacre was also the term used by Turkey’s foreign minister to describe the deaths.

Egypt now finds itself at a dangerous crossroad facing a dramatic escalation of tensions at home and increasing diplomatic pressure from abroad.

By CCTV correspondent Jack Barton

(Source: CNTV.cn)