A foreign national was killed and four others were wounded in an Israeli airstrike on the site of a United Nations headquarters in central Gaza City on Wednesday, Gaza's health ministry said.

The head of the U.N. Office for Project Services said the explosive ordnance was “dropped or fired” and the blast was not accidental.

The United Nations says an international staffer was killed and five others wounded in an explosion in the Gaza Strip. Jorge Moreira da Silva, head of the U.N. Office for Project Services, said the cause of Wednesday's blast remains unclear but that an explosive ordnance was “dropped or fired.