The US- and Israel-backed aid group said the attack, which the BBC could not independently verify, came after days of threats from Hamas.

Multiple aid workers were killed after a bus was attacked in Gaza on Wednesday night, according to a US-backed humanitarian aid organization which accused Hamas of carrying out the assault.

The group, which has been harshly criticized by the U.N. and other aid providers, said at least five people had died in an attack on one of its buses.