Palestinian sources say two police officers have been killed and several others wounded in an explosion in the northern Gaza Strip that destroyed a building used by Palestinian security forces.
A Palestinian Interior Ministry spokesman accused Israel in the incident at the Jabaliya refugee camp. But the Israeli army said it was not involved.
Israel has recently stepped up air strikes and artillery shelling against militant targets in northern Gaza, in response to ongoing rocket fire from Gaza militants targeting southern Israel.
Some information for this report was provided by AFP, AP and Reuters.