Tel Aviv/Gaza - Three Israeli soldiers were killed and 24 injured overnight by friendly fire, the Israeli military confirmed Tuesday.

An Israeli tank fired a shell by mistake at a building in which the soldiers had taken cover during fighting with armed Palestinians, a military spokeswoman said. One of the injured soldiers was in critical conditions and three others in serious condition, she said.

The incident raised the Israeli death toll in the ground offensive begun Saturday to four soldiers.

Fighting between the Israeli troops and local fighters of the Islamic Hamas movement intensified after darkness Monday. Witnesses reported heavy gunfire and shelling.

According to Israeli media, Israeli troops for the first time advanced into populated areas and destroyed several houses, while the Palestinian fighters confronted them with mortar shells. (dpa)