At least one person has died and three more have been injured after an explosion in a suburb of the Egyptian capital of Cairo.

The incident in Maadi on Friday morning occurred about the same time deposed former President Hosni Mubarak left Maadi Military Hospital, where he had been detained, after six years behind bars.

Security services said that the cause of the blast was not immediately known. No claim of responsibility has been made.

The Interior Ministry said in a statement that the man who was killed was a building guard who found an “unidentified metallic object”, which exploded when he picked it up. He was killed in the blast, and his wife and two children injured by shrapnel.

The neighbourhood in which the incident occurred has been closed off to the public while security services sweep the area.

Egypt’s security forces are the frequent targets of Islamist groups around the country as well as Isis-affiliated militants in the Sinai, which have flourished in the chaos that has engulfed Egypt since the 2011 revolution.

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​Mr Mubarak’s 30-year-rule ended when he was overthrown in January 2011. He later became the first leader to face trial after the Arab Spring protests that swept the Middle East.

The 88-year-old was cleared of the final murder charges against him earlier this month, after facing trial in a litany of cases ranging from corruption to the killing of protesters.