Medical workers retrieved three bodies from the rubble of the building.
Two others died less than a mile away after being struck while riding a motorbike. Israeli military officials said the two men were Hamas militants.
Some 70 targets in Gaza were hit since the end of the three-day truce, Israel Defense Forces said. About 60 rockets were fired at Israel, most of which struck open ground. One civilian in Israel was killed.
The Palestinian Ministry of Health said the death toll in Gaza has reached 1,900 since the beginning of the month-long war. There have been 67 Israeli deaths.
An Israeli military official, whose name wasn't reported, said Hamas has shifted toward using locally made rockets which have a shorter range than more sophisticated weapons used earlier in the month.
Notable deaths of 2014 [PHOTOS]
Syrian Al Qaida group executes Lebanese soldier