Hundreds of anti-government protesters have rallied across Egypt to mark the second anniversary of the killing of 50 Muslim Brotherhood supporters in the capital, Cairo.

Protests were held in Cairo, as well as in Alexandria and Giza to mark the July 8, 2013 killing of 50 supporters of Egypt’s first democratically elected President Mohamed Morsi, an incident commonly referred to as the Republican Guard massacre.

Protests, led mostly by Muslim Brotherhood supporters, also took place in the Nile Delta provinces of al-Sharqiya, al-Beheira, Kafr al-Sheikh, and al-Monoufiya.

Demonstrators also took to the streets in the provinces of Fayoum, Bani Suef, and Assyut.

During the 2013 act of violence, which took place five days after Morsi’s overthrow by then army chief and now President Abdel Fattah el-Sisi, 400 people were also wounded.

Back then, Egypt’s army attacked the protesters who were seeking to free Morsi from detainment inside a Republican Guard building in Heliopolis, in the capital, Cairo.

The Muslim Brotherhood said the protesters were killed in “cold blood.”

Commemorating the massacre’s anniversary, the Brotherhood warned the “butchers” that “retribution will be forthcoming, no matter how long it takes.”

Sisi stands accused of leading a crackdown on the supporters of the Muslim Brotherhood movement, with which Morsi is affiliated. Hundreds of anti-government protesters, mostly Brotherhood supporters, have been killed in clashes with Egyptian security forces following the overthrow of Morsi.

Morsi himself has been sentenced to death, along with a number of other Brotherhood members, on security-related charges dating back to the 2011 uprising that led to the ouster of the country’s former dictator, Hosni Mubarak.