JERUSALEM (JTA) — Israel’s Air Force struck targets in the Gaza Strip in response to rocket attacks on southern Israel.

Two weapons storage facilities in central Gaza and a rocket launch site in southern Gaza were hit Monday morning, the Israel Defense Forces Spokesman’s Office said in a statement.

Earlier on Monday morning six rockets were launched at southern Israel. Two of the rockets were intercepted by the Iron Dome missile defense system near Ashkelon, four others landed in open areas in southern Israel, with no injuries or damage reported.

It is believed that the rockets were not launched by Hamas, but instead by terrorist groups, such as Islamic Jihad, who are challenging Hamas’ rule.   Hamas reportedly has been working to keep the border with Israel calm in observance of the Egypt-brokered cease-fire following last year’s Operation Pillar of Defense.

“Last night’s rocket attack is an intolerable act of aggression against Israel and its civilians. Hamas is held accountable for all acts of terrorism deriving from the Gaza Strip. The IDF is determined to safeguard the State of Israel and will operate accordingly to do so,” said IDF foreign media spokesman Lt. Col. Peter Lerner.

Following the attack, the Coordination of Government Activities in the Territories on orders from Defense Minister Moshe Ya’alon announced that the Kerem Shalom cargo crossing will be closed until further notice in response to the attacks.