Gaza Strip ? Israeli troops struck deep inside the largest Palestinian refugee camp Thursday, battling masked gunmen in an unprecedented campaign to stop deadly rocket fire on Israeli towns. Twenty-eight Palestinians were killed and 131 wounded, the bloodiest single-day toll in fighting in 30 months.

Three Israelis — two soldiers and an Israeli female jogger — were killed in two Palestinian shooting attacks in northern Gaza.

Prime Minister Ariel Sharon approved a large-scale military operation in the northern Gaza Strip after meeting with advisers late Thursday, an Israeli official said. The plan was a response to the killing of two Israeli children, ages 2 and 4, by a Hamas rocket attack on an Israeli border town Wednesday. However, he stopped short of ordering a call-up of reserves.

The plan, which has the backing of Defense Minister Shaul Mofaz, was unanimously approved by the Israeli security Cabinet on Thursday night.

The approval clears the way for Israeli troops to move in force into the Palestinian towns of Beit Lahiya, Beit Hanoun and the sprawling Jebaliya refugee camp, an official said, speaking on condition of anonymity.

The army’s push Thursday into the center of Jebaliya — a first in four years of fighting — signaled a change in military tactics.

Since fighting erupted in 2000, the military has refrained from reoccupying large areas of crowded Gaza for long periods, for fear of getting bogged down in urban combat. The army has felt less constrained in the less densely populated West Bank.

Armored vehicles rolled into squalid Jebaliya, a militant stronghold with 106,000 residents, on Thursday morning. Throughout the day, masked Palestinians taking cover in camp alleys fired assault rifles — and occasionally anti-tank missiles and grenades — at tanks, which responded with machine-guns. Militants were seen laying explosive charges and unraveling detonation wire.

Palestinians run for cover from Israeli army fire at the Jabaliya refugee camp adjacent to Gaza City. Twenty-eight Palestinians and three Israelis -- a woman jogging in a Jewish settlement and two Israeli soldiers -- were killed Thursday in northern Gaza as Israeli troops pushed deep into Jabaliya, the largest Palestinian refugee camp in the northern Gaza Strip.

In the bloodiest incident, a tank fired a shell toward a group of gunmen, killing seven Palestinians and seriously wounding 23, including gunmen and civilians. Many of the wounded lost limbs, and at least four were under age 14, doctors said.

U.N. Secretary-General Kofi Annan expressed grave concern at the escalation of violence and “especially mourns the death and injuries of children,” U.N. spokesman Fred Eckhard said.

Kamal Adwan Hospital was overwhelmed by the influx, and doctors had to treat some patients on the blood-soaked floor and on cafeteria tables.