A large explosion struck outside the Italian Consulate in Egypt's capital Cairo early Saturday, severely damaging the building and killing one civilian, and injuring four others, officials said.

An Italian diplomat said the consulate was closed at the time and no staff members were wounded in the blast.

Heath Ministry official Hossam Abdel-Ghaffar told The Associated Press that at least one person was killed in the blast. The identity of victim was not clear, Abdel-Ghaffar said, adding that the victim's limbs were severed, suggesting he was close to the explosion.

A security official said the exact cause of the explosion was still unclear. Another official said investigators are looking the possibility of a car bomb; remains of a car were found in the area of the explosion. All officials spoke on condition of anonymity as they were not authorized to brief the media.

The state-owned Middle East News Agency quoted a security official as saying investigators are looking into whether an explosive device was placed under a car parked near the building.

Egypt has been witnessing a rising wave of violence in recent weeks. Less than two weeks ago, the country's chief prosecutor was killed in an explosion near his home in Cairo as he was heading to work. Days later, militants waged a coordinated and protracted attack on military installations in the restive northern Sinai province, leaving at least 17 soldiers dead in one of the most brazen attacks on troops in the area.

The blast early Saturday ruptured underground water pipes, flooding the area. It heavily damaged the building which is based in one of the busiest intersections in Cairo, a major artery that connects Ramsis Square to the heart of downtown Cairo.

Civilians gathered around the area of the explosion, as police cordoned off the streets leading to the consulate.

Police ringed off the area with tape before investigators arrived. Several foreign journalists briefly detained on the scene by police but later released.

Charred car parts were scattered onto the street. Several floors of the consulate were destroyed on one side, leaving a gaping hole with bricks spilling from it and its red facade peeling off.

"I was sleeping when the explosion went off, it blew in my window and when I went outside the air was full of dust," said Ahmed Hasan, 20, a neighbour whose leg had minor cuts. He said the bomb went off at 6:20 am and he saw someone with a severed leg.