"At least 421 people died when security forces stormed two camps which supporters of ousted leader Mohammed Morsi set up in the city last month," BBC reported.
A state of emergency was declared following the violence and curfews were imposed in cities across Egypt.
Meanwhile, the US condemned the violence in Egypt.
US Secretary of State John Kerry said: "The United States strongly condemns today's violence and bloodshed across Egypt. It's a serious blow to reconciliation and the Egyptian people's hopes for a transition towards democracy and inclusion."
"In the past week, at every occasion, perhaps even more than the past week, we and others have urged the government to respect the rights of free assembly and of free expression, and we have also urged all parties to resolve this impasse peacefully and underscored that demonstrators should avoid violence and incitement," he said.
"Today's events are deplorable and they run counter to Egyptian aspirations for peace, inclusion, and genuine democracy. Egyptians inside and outside of the government need to take a step back," Kerry said.
United Nations Secretary-General Ban Ki-moon also condemned the violence that occurred Wednesday in Cairo when Egyptian security services used force to clear sit-ins and demonstrations, and urged all Egyptians to focus on promoting inclusive reconciliation.
The crackdown comes just days after Ban renewed his call for all sides in Egypt to reconsider their actions in light of new political realities and the imperative to prevent further loss of life.
"The Secretary-General regrets that Egyptian authorities chose instead to use force to respond to the ongoing demonstrations," his spokesperson said in a statement.
Ban extended his condolences to the families of those killed and his wishes for a full and speedy recovery to those injured.
"In the aftermath of Wednesday's violence, the Secretary-General urges all Egyptians to concentrate their efforts on promoting genuinely inclusive reconciliation," his spokesperson said.
"While recognizing that political clocks do not run backwards, the Secretary-General also believes firmly that violence and incitement from any side are not the answers to the challenges Egypt faces," he said.
After days of protests, the Egyptian Army on July 3 ousted the country's first democratically elected president Morsijust after one year in office.
He was taken into military custody the same night.
The head of country's Supreme Constitutional Court, Adly Mansour, was sworn in as interim president on July 4.
Demonstrators across the nation accused Morsi of failing to tackle the economic and security problem since being elected a year ago.
--IBNS (Posted on 15-08-2013)