Israel defied growing international calls for a ceasefire Saturday, killing 15 people in an airstrike on the home of Gaza’s police chief, according to health officials in the besieged enclave. Rocket launches from Palestinian fighters in the territory likewise continued unabated, but with no reports of any resulting fatalities.

The attack targeting a senior Gazan police officer, the deadliest singel strike since Israel launched its offensive five days ago, took place as people were ending evening prayers at a mosque near the target, according to Health Ministry official Ashraf al-Kidra.

It raised the Palestinian death toll to 151. At least 88 civilians, including 30 children, have been killed since Tuesday, according to a report by the United Nations. The escalation of airstrikes on Gaza has been met by continued rocket launches from armed groups in the territory. On Saturday, nearly 700 projectiles were fired on Israel, originating from both Gaza and southern Lebanon.

It comes despite the U.N. Security Council calling for a ceasefire in the hostilities Saturday. In wording approved by all 15 members called for de-escalation of the violence, restoration of calm and a resumption of direct negotiations between Israel and the Palestinians.

Meanwhile in a statement Saturday, the Israeli military said it was ordering Palestinians living in the northern Gaza Strip to evacuate the area "for their own safety." Brig. Gen. Motti Almoz, the chief military spokesman, said Israel planned to hit the area with heavy force in the next 24 hours as it steps up an offensive against Gaza militants.

Earlier Saturday, a dozen people were killed in Gaza by Israeli military strikes on a mosque, a rehabilitation center and a charitable association for the disabled.

Three patients and a nurse were killed in the explosion on the rehabilitation center in Jebaliya. At least two people were killed and four critically wounded in an attack on a home for the disabled in Beit Lahiya, according to the AFP news agency. Meanwhile, three people were killed in the eastern Tufah area of Gaza City, and three in western Gaza City.

A mosque in Al-Nuseirat, in central Gaza, was also destroyed in the overnight raids. Graffiti scrawled on one of the mosque's blasted walls read, "We will prevail despite your arrogance, Netanyahu."

On Saturday, Israel's army chief, Lieutenant-General Benny Gantz, said his forces were ready to act as needed — hinting at readiness to send tanks and ground troops across the barbed-wire boundary into Gaza, as Israel last did for two weeks in early 2009. Some 20,000 reservists have already been mobilized for a possible thrust into Gaza, the army said.

"We are in the midst of an assault and we are prepared to expand it as much as is required, to wherever is required, with whatever force will be required and for as long as will be required," Gantz told reporters.

In anticipation of more violence, the U.N. and a handful of consulates are preparing for an exodus of 800 dual- and foreign-nationals from 21 countries on Sunday morning through the Erez Crossing at the northern end of the Gaza strip, according to a U.N. official.

In other developments, rockets fired from Lebanon hit Israeli territory on Saturday, the second such incident in two days. The Israeli military responded with artillery fire, according to Lebanese security sources and the Israeli military.

"Initial reports indicate that at least two rockets fired from Lebanon hit open areas north of Nahariya. No damage or injuries, thus far," an Israeli military statement said, adding that Israeli forces had fired artillery toward the source of the rocket fire.

Southern Lebanon is a stronghold of Hezbollah — a Shi'ite group that battled Israel seven years ago — but there are also Palestinian groups in the same area.

Hamas, battling with Israel from Gaza, claimed responsibility for the rocket fire from Lebanon.

Al Jazeera and wire services