At least 42 people were reported killed after Egyptian troops opened fire on pro-government supporters early Monday.

According to the statement of Muslim Brothers, at least 35 people were killed as soldiers and policemen attacked the pro-Mursi demonstrators at the sit-in which started after the morning prayer outside headquarters of Egypt's Republican Guard. Rubber bullets were used in the attack.

A high-senior executive said in a statement to AFP that the number of people killed in the bloody attack was 42.

According to the state television Al-Ahram, Egyptian military launched an attack on the headquarters of Republican Guard in Cairo after a “terrorist group” tried to storm the building at down. The television said one officer was killed and many other soldiers were wounded, six critically, in the attack against military and police forces.

Four demonstrators had been killed in clashes with soldiers in front of the headquarters last Friday. According to the Ministry of Health, 29 people were wounded during the demos of anti-Mursi protestors in Cairo and Alexandria on Sunday.

Following today's attack, the Freedom and Justice Party (FJP), the political party of the Muslim Brotherhood, called on Egyptians to rise up against those who "want to steal the revolution using armored vehicles".

The Al-Nour Party (Hizb Al-Nour), a new political Salafi party, has in the meantime announced its withdrawal from the meetings with the government for the assignment of the new prime minister. The party said its withdrawal was due to its reaction against the "massacre" outside headquarters of Republican Guard.

Egptian armed forces overthrew the Islamist Morsi government last Wednesday after hundreds of thousands took to the streets in mass, demanding the government's resignation. Supporters of Muslim Brotherhood have been staging daily protests ever since, demanding that Mursi come back to power.