GAZA CITY, Gaza Strip — Israel fired surface-to-surface rockets at Gaza City police headquarters and the offices of Palestinian leader Yasser Arafat's Fatah movement Thursday in retaliation for a roadside bomb that killed two Romanian workers employed by Israel.

Dozens of people were hurt in the shelling, most of them lightly, doctors said. A 3-year-old boy had cuts on his face and ears after being hit by shards of glass.

At least four rockets struck Gaza City on Thursday afternoon, sending black smoke into the air. Palestinian policemen ran out of the walled security headquarters in the center of town, while ambulances rushed inside, even as rockets crashed down with loud booms.

Palestinian Planning Minister Nabil Shaath said Arafat was not harmed in the attack, which he called "a war of terror Israel has declared on the Palestinians."

Palestinian Police Lt. Ahmed Abbas said he was sitting on a chair in the courtyard when one of the rockets hit. He said he was thrown into the air and the ground shook under his feet.

The Israeli army said the rockets were fired in retaliation for the killing of the Romanians earlier in the day. The Romanians, employed by Israel, had been working on the border fence when a roadside bomb went off. A third worker was injured by the blast.

Three rockets hit the Palestinian police headquarters, and a fourth struck Fatah offices about 400 yards east of Arafat's seaside headquarters. The faade of the Fatah office's second floor was knocked out, and black smoke came out of the building.

On Wednesday, the bodies of two Israeli boys, one an immigrant from Maryland, were found bludgeoned to death by rocks in a cave in the West Bank.

The boys, Koby Mandell, 13, and Yossi Ishran, 14, had gone on a hike near their home in the West Bank settlement of Tekoa on Tuesday, and were seized, presumably by Palestinians, and killed. Newspapers quoted police as saying the boys' heads were so badly disfigured that facial identification was impossible.

"Stoned to death," read the headline in the Yediot Ahronot daily Thursday, using the single Hebrew word "Skila," which refers to one of four forms of capital punishment in ancient Jewish law.

Koby's family immigrated and settled in Tekoa in 1996. Twenty-one Palestinians were arrested in connection with the killing.

Israeli Prime Minister Ariel Sharon said he was revolted by the killings of the Israeli teen-agers. "It was a heinous deed in which children were intentionally attacked," Sharon said.

Asked whether Arafat was still a potential negotiating partner, Sharon said that "anyone who causes the killing of Israeli citizens cannot be a partner." If violence stopped, Israel would be ready to resume peace talks, Sharon said.

Arafat, when asked about the killings, responded by saying that Palestinian children have been victimized by Israel.

In an apparent response to the explosion in Gaza on Thursday, Israeli bulldozers razed Palestinian farmland and a police station near Kissufim, the fifth incursion into Palestinian territory in two days.

Overnight, Israeli troops destroyed four homes and a Palestinian police station in the Rafah refugee camp, and 12 Palestinians were hurt.