GAZA CITY, Palestinian Territories: Israeli air strikes hit the cabinet headquarters of Gaza’s Hamas government on Saturday after militants fired rockets at Jerusalem and Tel Aviv as Israel called up thousands more reservists in readiness for a potential ground war.

The Israeli military said that it had sealed off all the main roads around the Gaza border, declaring the area a closed military zone, in the latest sign that Israel’s patience with the rocket fire was at an end and it was poised to launch its first ground offensive on the territory since 2008-2009.

The Hamas government said that its cabinet headquarters was targeted with four strikes and witnesses reported extensive damage to the building.

“The IDF [Israel Defense Forces] has targeted [Hamas prime minister] Ismail Haniya’s headquarters in Gaza,” an Israeli army spokesman said “Over the past six hours, the IDF targeted 85 more terror sites. The headquarters was completely destroyed and neighboring houses were damaged as a result of the barbaric Israeli bombing.”

The raid on the building came as Israel renewed strikes across Gaza, bombing the headquarters of the Hamas police force in western Gaza City and the government’s internal security headquarters in the north of the city.

President Barack Obama reiterated US support for Israel’s right to defend itself during a call with Israeli Prime Minister Benjamin Netanyahu about the conflict in Gaza.

Israeli air strikes on Gaza on Friday night killed six Palestinians, raising the toll in two days of violence to 30, a Hamas health ministry spokesman said.

An Israeli military spokesman said one strike destroyed a Hamas military drone production workshop.

Israeli ministers approved the call-up of as many as 75,000 reservists as Netanyahu held late evening talks at the defense ministry in Tel Aviv with his inner circle, Channel Two television reported.

The military wing of the Islamist Hamas movement that rules Gaza said it fired the rocket at Jerusalem, the first from the territory ever to strike the outskirts of the Holy City.

It marked a major escalation by Hamas in the face of a deadly pounding since Wednesday by Israeli aircraft that has sparked outrage across the Arab and Islamic world.

Neither rocket on Friday caused casualties or damage, police said, but they sowed panic in both of the Jewish state’s main population centers, setting off warning sirens and sending people scurrying to shelters.

One hit a Jewish settlement bloc in the occupied West Bank just south of Jerusalem, which is home to many commuters, but caused no damage or injuries, an army spokesman said.

A second rocket crashed into the sea off Tel Aviv—some 200 meters from the beachfront US embassy, sending beachgoers fleeing, a witness said.

UN and Palestinian officials said that UN Chief Ban Ki-moon would travel to the region in days to push for a truce.