A defiant Muslim Brotherhood Thursday vowed to bring down the military-backed government after Egypt witnessed its bloodiest day since the Arab Spring with at least 421 people killed in a crackdown by security forces on supporters of ousted President Mohammed Morsi.

“We will always be non-violent and peaceful. We remain strong, defiant and resolved,” Brotherhood spokesman Gehad El-Haddad wrote on his Twitter account.

“We will push (forward) until we bring down this military coup,” Haddad said.

At least 421 people were killed and more than 3,500 injured during clashes in the country Wednesday after security forces evicted supporters of Morsi from two protest camps, the health ministry said, according to the state-run EGYNews site.

Those killed included 43 police officers, the interior ministry said.

The Muslim Brotherhood claimed that more than 2,000 people had been killed in the violence.

Egypt’s Army-backed interim Prime Minister defended the deadly operation by security forces against supporters of Morsi camped at Rabaa al-Adaweya and al-Nahda.

In a televised statement Wednesday, Hazem el-Beblawi said the decision to break up the protests “was not easy” and came only after the government had given mediation efforts a chance.

“We found that matters had reached a point that no self respecting state could accept,” Beblawi said, citing what he describes as “the spread of anarchy and attacks on hospitals and police stations.”

Bulldozers were said to been used to uproot the camps and drive out the protesters who were seeking Morsi’s reinstatement after the 62-year-old Islamist was ousted by the military on July 3.

The government Wednesday imposed a month-long emergency after riot police backed by armoured vehicles, bulldozers and helicopters swept away the two encampments of pro-Morsi supporters.

Security forces shot dead scores of people in their assault on the camps, defying international pleas to show restraint after a six-week standoff with Morsi’s Muslim Brotherhood supporters, Al Jazeera news channel reported.

Vice-president Mohamed ElBaradei resigned Wednesday, saying peaceful means could still have been found to end the confrontation, but other members of the government have rallied behind the decision to use force.

ElBaradei announced his resignation saying that, “(He) can no longer bear responsibility for decisions that (he does not) agree with, and whose repercussions he dreads. (He) cannot be responsible for a single drop of blood before God, (his) conscience, and (his) people, especially that (he) believes the dropping of that blood could have been avoided.”

ElBaradei’s resignation sparked mixed reaction among Egyptian youth and political elite alike. Tamarrod (Rebel) movement accused ElBaradie of “quitting at a historic moment.”

Meanwhile, Beblawi said the emergency would be for the shortest period possible. He said that the government was committed to an Army-backed road map to restore democracy.

The measure, scheduled to last for a month, also imposes a curfew in Cairo and several other provinces between 7 pm (10.30 pm IST) and 6.00 am (9.30 am IST).

“There was a need for the state to intervene with an extraordinary measure which is the emergency law. God willing, we will continue. We will build our democratic, civilian state,” Beblawi said.

Two journalists were killed during the violence Wednesday. Mick Deane, a cameraman for the UK-based Sky News channel, and Habiba Abd Elaziz, a reporter for the UAE-based Xpress newspaper, died from bullet wounds.

International condemnation of the violence was swift, with the US secretary of state John Kerry calling it “deplorable.”

The United Nations, the European Union, Britain, France, Iran, Qatar and Turkey strongly denounced the use of force by the military-backed interim government.

EU foreign policy chief Catherine Ashton called on security forces to “exercise utmost restraint.”

The interior ministry had issued a statement earlier saying security forces were taking “necessary measures” against the protesters.

In a press conference, the cabinet media adviser Wednesday thanked the security forces for “exercising self-control and high-level professionalism in dispersing the sit-ins,” and held the Muslim Brotherhood responsible for “escalation and violence.”

Witnesses said that after firing tear gas into the Rabaa al-Adawiyeh sit-in, pandemonium struck among the thousands of protesters.