Egypt: Muslim Brotherhood accuses military of ‘massacre’ after Morsi supporters shot dead (VIDEO, PHOTOS)

Egypt's interim head of state, Adly Mansour, on Monday issued a timetable for political reforms, vowing that parliamentary elections will be held within six months, after which a date can be set for presidential elections, according to the Associated Press.

Mansour also promised a referendum on an amended constitution within four-and-a-half months,  reported Reuters, meaning parliamentary elections will probably be held sometime in February. Egypt's new constitution has been the subject of much debate and is currently suspended.

After a new parliament has been assembled, lawmakers will have one week to set a date for new presidential elections, said the AP. 

Meanwhile, political upheaval in Egypt continues. The Muslim Brotherhood has called for an "uprising" after dozens of its supporters were shot dead in Cairo early Monday as they staged a sit-in in support of Egypt's deposed president, Mohamed Morsi. 

According to the Brotherhood, at least 53 people, including children, were killed outside the Republican Guard military compound in what the group is calling a "massacre."

Emergency services later told Egyptian media that the death toll had reached 51, with more than 400 wounded. Al Jazeera was told by one doctor that "the majority of injured had gunshot wounds to the head," a detail corroborated by other reports.  

Witnesses told Agence France-Presse that soldiers and police began firing into the air and tear gassing pro-Morsi protesters during dawn prayers, then gunmen in civilian clothes opened fire directly onto the crowd. 

Yet the military claimed an "armed terrorist group" had attempted to storm the compound, where the army is believed be holding the former president since it ousted him on Wednesday.

The UK-based newspaper the Telegraph quoted activist Ahmed al-Nashar saying there was no attack on the Republican Guard base and that unidentified "thugs" started the killing.

In a statement broadcast on state TV, the military said around 200 people had been arrested and a large stash of weapons and ammunition seized, the BBC reported. One army officer was killed, the statement said.

The Muslim Brotherhood's political wing, the Freedom and Justice Party, called for "an uprising by the great people of Egypt against those trying to steal their revolution with tanks," AFP reported.

The party urged other countries to intervene to "stop further massacres… and prevent a new Syria."

In the hours after the shooting, security forces reportedly blocked off access to the site as well as other parts of central Cairo.

Meanwhile the ultra-conservative Islamist Nour party, which initially backed the military's intervention, said it was withdrawing from talks on forming an interim government in protest at the shooting.

After news of the killings broke, Nobel laureate and candidate for Egypt's presidency, Mohamed ElBaradei, condemned the brutal violence:

Here is some raw video from the AP and NewsPoint. Warning: Some of the images may be graphic.

Egypt forces use guns, teargas against pro-Morsi protesters [Credit: Ahmad Alhelly]

A makeshift hospital [Credit: Madaney Mohamed/NewsPoint]