The attack happened in Abu Zaabal, an industrial suburb of the capital Cairo, on Monday as people participated in an anti-government protest after the Eid al-Fitr prayers. The rally was organized by the Anti-Coup Alliance which includes the now-outlawed Muslim Brotherhood.
According to reports, at least 25 protesters have been injured, with five of them in critical condition.
The Freedom and Justice Party, the political arm of the Muslim Brotherhood, also confirmed the deaths on its Facebook page.
Also on Monday, a woman was killed and several others injured during protests in Nasr City in eastern Cairo.
Since Mohamed Morsi’s ouster last July, his supporters have staged regular protests against the new authorities.
Morsi, Egypt’s first democratically-elected president, was toppled in a military coup led by Abdel Fattah el-Sisi, Egypt’s current president and then army commander.
Following the ouster, Sisi announced his candidacy for the nation’s presidency and was sworn in as president after winning an election in which less than 50 percent of eligible voters participated.
Sisi is accused of leading the suppression of Muslim Brotherhood supporters as hundreds of them have been killed in clashes with the Egyptian security forces over the last year.
This is while the Egyptian military-installed judiciary has provoked international outrage over mass death sentences issued for people in several mass trials.
Rights groups say the army’s crackdown on supporters of Morsi has left over 1,400 people dead and 22,000 arrested, while some 200 people have been sentenced to death in mass trials.