GAZA CITY (Ma'an) -- The UN agency for Palestinian refugees on Wednesday condemned an Israeli attack on one of its schools used to house thousands of internally displaced Gazans earlier the same day.
"Last night, children were killed as they slept next to their parents on the floor of a classroom in a UN designated shelter in Gaza," UNRWA's Commissioner-General Pierre Krahenbuhl said in a statement.
"Our initial assessment is that it was Israeli artillery that hit our school, in which 3,300 people had sought refuge. We believe there were at least three impacts," the statement said.
"The precise location of the Jabalia Elementary Girls School and the fact that it was housing thousands of internally displaced people was communicated to the Israeli army seventeen times ... to ensure its protection."
The statement went on to say that the incident was the sixth time an UNRWA shelter had been struck during Israel's offensive on Gaza.
"UNRWA condemns in the strongest possible terms this serious violation of international law by Israeli forces," spokesman Chris Gunness tweeted.
Gaza's health ministry said earlier that at least 16 people were killed in an Israeli shelling on a UN school in Jabaliya camp. The ministry called on UNRWA to immediately condemn the attack.
An Israeli army spokeswoman told Ma'an later that initial reports suggested Palestinian militants had fired mortar shells at Israeli soldiers from the vicinity of the school.
The Israeli army responded by firing back at the "origins of fire," the spokeswoman said.
"The incident is still being reviewed," she added.
Over 70 Palestinians have been killed by Israeli forces so far on the 23rd day of the Israeli offensive, bringing the three-week total above 1,300.
More than 200,000 people, or about one in eight Gazans, have been forced to leave their homes as a result of the assault.