The United Nations says a teacher who worked for a relief agency was killed in Gaza by Israeli air strikes.

The U.N. Relief and Works Agency for Palestine Refugees in the Near East said that Marwan Abu El Qumsan was killed Wednesday. El Qumsan was in his early 50s and taught Arabic at UNRWA's Preparatory Boys School in Jabalia, and was in a car near the scene of an airstrike, the agency said in a statement.

The agency said the violence in Gaza forced it to close its schools temporarily.

Also Thursday, the UN Office for the Coordination of Humanitarian Affairs said the escalating violence has triggered widespread fear on both sides of the border, and the humanitarian situation in Gaza "remains precarious."