Palestinians fired two Qassam rockets at Sderot, moderately injuring one man Tuesday morning, 24 hours after a young child and a 49-year-old man were killed by a rocket that landed beside a nursery school in the western Negev town.

Responding to the Monday attack and to the Sunday bombing of an IDF strongpoint in the Gaza Strip, Israel sent troops, bulldozers and tanks into the northern Strip early Tuesday. The push began with a late Monday air strike on a Hamas-linked media center in Gaza.

The Monday deaths of the four-year-old and the man, 49, marked the first time in nearly four years of fighting that Israelis were killed by rockets from Gaza.

Palestinian security sources said Tuesday that a Palestinian had been killed in the IDF raid, but the circumstances of his death remained unclear. Israeli media reported that the victim was a Hamas man setting a bomb in the path of oncoming Israeli troops.

Israeli security sources said the operation could be a precursor to a prolonged operation in Gaza to prevent rocket fire on Israeli towns bordering the Strip.

One of the Qassams in the Tuesday shelling landed in an industrial area on the outskirts of the town, the other in an open area outside the city.

Prime Minister Ariel Sharon's Sycamore Ranch home is located just outside Sderot, and is believed to be the target of many of the salvos of Qassam missiles, which are unguided and may stray widely from their intended course.

Shortly after midnight Tuesday, Israeli helicopters fired three missiles into a 16-story building housing the Hamas-linked media center Al-Jeel, injuring two people, witnesses said.

Minutes later, helicopters also fired a missile at a building housing a metal workshop in the Nusseirat refugee camp in central Gaza, witnesses said

The fatal rocket attack on Monday morning followed a Sunday bombing in which IDF Staff Sergeant Roi Nissim was killed and five troops were wounded. Targeting an IDF stronghold, militants detonated 150 kilograms of explosives placed in a tunnel they had dug underneath the post in the central Gaza settlement bloc of Gush Katif.

The high-rise targeted by the IAF Monday night houses several media outlets, including the Arab TV satellite station Al Jazeera. White smoke rose from the building and ambulances raced to the scene.

The missiles hit a third-floor media center affiliated with the Islamic militant group Hamas. Two people suffered moderate injuries, doctors said.

The army confirmed targeting the building, saying in a statement the office was "a communication center which maintained constant contact with terrorists [and] through which Hamas claimed responsibility for terrorist attacks."

The foundry was said to be destroyed in the strike, with no reports of casualties. The IDF said Hamas had used the foundry to manufacture weapons.

Late on Monday, IDF troops destroyed two eight-story buildings in the Khan Yunis refugee camp in the Strip.

The decision to destroy the buildings was taken in a meeting between Sharon and security chiefs to discuss an Israeli response to the two attacks. Present at Sharon's two-hour discussion were Defense Minister Shaul Mofaz, Chief of Staff Moshe Ya'alon and the heads of Military Intelligence and the Shin Bet security services, Israel Radio said.

Following the attacks, Mofaz cancelled a trip to Italy later in the week.

Hours later, IDF troops blew up the two empty eight-story buildings, located close to Gush Katif. The two buildings were destroyed after troops found a ventilation shaft between them, which military sources said was apparently connected to the explosives-laden tunnel.

The victims of the Sderot attack, Mordechai Yosepov, 49, and four-year-old Afik Zahavi, were laid to rest Monday afternoon at the Sderot cemetery. The boy's mother, Ruthie, was critically wounded in the attack.

Both Hamas claimed responsibility for the rockets, which were fired from the Gaza Strip. Since the start of the intifada in September 2000, 347 Qassam rockets have been fired at Israeli targets, of which 265 have landed within the Green Line.