At least 36 Islamist prisoners were killed on Sunday during an attempted jailbreak in Egypt, police said.
The deaths brings the number of people dead in Egypt’s recent violence to 800.
The Egyptian interior ministry said the prisoners had taken an officer hostage and died after suffocating on tear gas.
“Thirty-six of the prisoners died of suffocation and crowding after tear gas was used to stop their escape,” the ministry said.
The killings were the latest in five days of bloodshed sparked by a bloody police and military operation to clear Islamists from protest camps in Cairo.
In his first remarks since the campaign was launched, military chief Abdel Fattah al-Sisi, who overthrew Morsi on July 3, warned security forces would confront any further violence from protesters.
“We will never be silent in the face of the destruction of the country,” Sisi told top military and police commanders.
Meanwhile , the United States has announced the cancellation of its biannual military exercise with Egypt, and its embassy in Cairo was closed Sunday for security reasons.
The White House has stopped short of suspending $1.3 billion in annual aid, although some US lawmakers called Sunday for the funds to be cut.