Updated

The Israeli army says a tank has fired at a target in the northern Gaza Strip following an explosion on the Palestinian side of the border.

The army says it's trying to determine the source of the explosion, which took place on Wednesday. Earlier, a tank fired into Gaza after a mortar shell was launched toward Israeli forces near the southern Gaza Strip.

The army said no soldiers were harmed, and there were no immediate reports of casualties on the Palestinian side.

Israel and Gaza's Islamic militant Hamas rulers have largely observed a cease-fire since a 50-day war in 2014, but other militant groups also operate in Gaza. Israel holds Hamas responsible for any attacks out of the territory.