The four-storey building, which was empty at the time of the strike, was flattened by the blast, which occurred at around 4 pm. The casualties suffered shrapnel wounds while celebrating a wedding at a nearby structure.
Photo: AP
"It felt like an earthquake," said Umm Fahmi, a woman who lives across from the blast site.
"My house did not only shake, it jumped from its foundations and back down. How could they drop such a bomb in a residential area on top of people's heads?" she said, peering through the dust at the concrete and steel remains of the security complex.
It was the first Israeli bombing of a Palestinian government building since Hamas Islamists seized control of Gaza in June after routing secular Fatah forces loyal to President Mahmoud Abbas .
Sources in Gaza said a second Israeli air strike minutes later damaged Hamas' so-called naval headquarters in the central Gaza Strip, adding that the IDF also opened fire at the northern town of Beit Hanun. No injuries were reported in either incident.
The IDF confirmed that fighter jets struck a Hamas position in central Gaza, as well as the Islamist group's headquarters in the northern Strip in response to the heavy rocket barrages firedtoward the western Negev.
It was later reported that Israel sealed all border crossings with Gaza on Friday, cutting off the flow of vital supplies to the besieged territory in an attempt to stop the rocket attacks.
Earlier in the day one Palestinian was killed and three others were injured in an Israel Air Force strike near the Jabalya refugee camp, which, according to the IDF, targeted a Qassam rocket-launching cell.
Hanan Greenberg and Reuters contributed to the report