At least three policemen and one civilian were killed in a blast at an apartment on Thursday in Giza, east of Cairo, the Interior Ministry said in a statement.

Thirteen people were wounded, the ministry statement said, without specifying if they were civilians or policemen.

According to the ministry, the suspects, who it said were affiliated with the banned Muslim Brotherhood group, were planning attacks and had been making explosives at an apartment in Haram district near the famed Pyramids.

The explosives went off as security forces raided the apartment, the statement added.

“Police had information that a group of Muslim Brotherhood members were preparing to carry out aggressive acts in the coming days using explosives and crude bombs,” the ministry said on its Facebook page.

“This group was using an apartment in a Cairo building, and on Thursday night the police raided this apartment where they found a number of crude bombs.

“When the bomb squad expert were dealing with one of the bombs, it exploded killing three policemen, one civilian and two unidentified men.”

Egypt has seen a wave of attacks since the military deposed President Mohamed Morsi in 2013.

The explosion in the capital’s Al-Haram district, near the pyramids, came ahead of next week’s anniversary of the 2011 revolution that ousted longtime autocrat Hosni Mubarak.

The interior ministry has warned against any “chaos” on Monday, and has boosted security across Egypt, including around the capital’s iconic Tahrir Square — epicentre of the anti-Mubarak revolt. Al Jazeera