UNITED NATIONS, Nov. 15 (Xinhua) -- A UN agency working for Palestinian refugees said that one of its teachers was killed in northern Gaza on Thursday by an Israeli airstrike, UN spokesman Martin Nesirky told reporters here.

"The UN Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) says that one of its teachers was killed on Thursday by an Israeli airstrike in northern Gaza," Nesirky said at a daily news briefing here.

"Marwan Abu El Qumsan, an Arabic teacher at the Agency's Preparatory Boys School in Jabalia, was killed, while his brother was severely injured," Nesirky said.

The Relief and Works Agency expressed its condolences to Marwan 's family on their tragic loss and reiterated its concern about the escalation of violence, which puts civilians on both sides of the conflict at risk, he said.

An Israeli air strike on Gaza killed three Palestinians on Thursday, bringing the death toll in the latest Israeli military offensives against Gaza militants to 11, reports said.

The atmosphere in the Gaza Strip on Thursday is similar to the early 2009, when Israel waged a three-week war on the Palestinian territory and called it "Operation Cast Lead," which left 1,440 Palestinians killed and 50,000 others injured, said the reports.