Jerusalem ? U.S. Ambassador Daniel Kurtzer, once a student at Jerusalem’s Hebrew University, denounced Palestinian terror attacks and laid a wreath at the school Thursday after a bomb detonated by a cell phone killed seven people five of them Americans.

“We have grieved with all the people of Israel as they have faced Palestinian terrorism,” said Kurtzer, speaking in front of the Frank Sinatra International Students Center, where the blast tore apart a cafeteria a day earlier. “Now that five American citizens have been killed, our grief is even deeper.”

The militant group Hamas claimed responsibility for the cafeteria blast at the Mount Scopus campus of Hebrew University, a popular gathering spot for Jewish, Arab and foreign students. Hamas called it revenge for an Israeli attack last week in Gaza that killed the leader of its military wing and 14 others, including women and nine children.

The U.S. citizens included an Israeli-American and a French-American, police said Thursday. Israelis, Arabs, as well as four Americans and three South Koreans were among the 80 wounded.

Unlike other recent Palestinian attacks, Wednesday’s attack was not a suicide bombing. The bomb, laden with nails and other metal objects, was in a bag left on a table in the center of the cafeteria and was detonated remotely by cellular phone, said an Israeli official, speaking on condition of anonymity.

Police detained a number of Arab employees of the university on suspicion of having aided the bomber, said a police official, also speaking on condition of anonymity.

Kurtzer, who took Middle Eastern studies at the university in 1969-70, placed a wreath in front of the cafeteria Thursday and observed a moment of silence.

“The terrorist murderers those who sent them and those whose action and inaction contributed to this despicable act have descended to a new depth of depravity,” he said. “They have violated the sanctuary of a university, in which Israelis, Arabs, Jews, Muslims and Christians study together.”

The university student newspaper, “Student Legends,” had printed two articles in April warning of lax security at the university, including one that imagined a suicide bomber blowing himself up inside the Sinatra cafeteria, killing seven people, said editor-in-chief Yaniv Tohorylef.

He said the cafeteria was in a particularly vulnerable position near a fence, and the newspaper’s scenario envisioned the bomber crossing the fence onto campus. At the time, the university assured students security was under control, he said Thursday.

Israeli police canceled training courses and put officers, including those with administrative jobs, on active duty in Jerusalem and elsewhere, police said. Checkpoints were also erected in the Sharon area of central Israel amid warnings that armed Palestinians had entered from the West Bank.

In the West Bank town of Nablus, Israeli troops who had remained on the edge of town moved into the city center. Residents who had defied the army-imposed curfew for four days stayed home.

The attack came as Israel’s Security Cabinet considered ways to stop or at least hinder suicide bombers, including measures such as expelling relatives of bombers from the West Bank to Gaza or destroying their houses.

In the Palestinian town of Beit Jalla, next to Bethlehem, the Israeli military destroyed the family house of Hazem Atta Sarasara, who carried out a suicide bombing attack on Tuesday in Jerusalem that wounded seven Israelis, the military said in a statement. Military sources said the destruction was a deterrent measure to show that such actions carry a price.

Israeli troops in the West Bank town of Jenin also demolished the home of an Islamic Jihad activist arrested earlier this week, residents said. The army said it was checking the report.

In new violence Thursday, a 27-year-old Israeli man, his hands and feet bound, was found dead with a gunshot wound to the head in his factory office near the Palestinian town of Tulkarem in the northern West Bank, police and the army said.

Brig. Gen. Gershon Yitzhak, the divisional commander of the West Bank, told Israel Radio the attackers were believed to be Palestinians who had taken advantage of the lifted curfew in Tulkarem on Thursday.

Meanwhile, two Palestinian universities, Al Quds on the edge of Jerusalem and Bethlehem University, sent their condolences to their families of Wednesday’s bomb blast at Hebrew University.

In an ad published in the Israeli daily Haaretz, the Palestinian universities said they “share in your sorrow over the murder of your dear ones and the repugnant attack.”

Police and family members identified the American dead as Benjamin Blutstein, 25, of Susquehanna Township, Pa.; Marla Bennett, 24, of San Diego; and Janis Ruth Coulter, 36, who worked in New York.

The others were David Gritz, 24, who holds dual American-French citizenship; and an Israeli with American citizenship whose name was not released, Jerusalem Police spokesman Kobi Zrihen said.

The two slain Israelis, Lavina Shapira, 53, and David Ludovisky, 29, were to be buried Thursday in Jerusalem.

In the Gaza Strip, an estimated 10,000 people rallied on Wednesday night to celebrate the bombing attack and endorsed calls for more “martyrdom operations.”

A leading Hamas official, Abdel Aziz Rantisi, said Thursday it did not matter that mostly Americans, and not Israelis, were killed in Wednesday’s attack since it was an attack against Israeli occupation.

“We are fighting on our occupied land, and we didn’t go to America or France,” he said. “It is better for America and France to advise their citizen not to go to a war and resistance territories.”

Spencer Dew, 26, an American student from Owensboro, Ky., who was lightly wounded by flying glass, said he had worried about such attacks in Israel, “but it didn’t deter me from coming. I assume I’ll come back next year.”

The Palestinian Authority condemned the attack but said it considered Israeli Prime Minister Ariel Sharon “responsible for this cycle of terror.”

The 22-month Palestinian-Israeli conflict has been marked by more than 70 Palestinian suicide bombings, killing more than 250 people. Wednesday’s attack was one of the deadliest not perpetrated by a suicide bomber.

Israeli troops control seven of the eight main Palestinian centers in the West Bank, moving in after back-to-back suicide bomb attacks in Jerusalem June 18-19. The university bombing and a suicide attack the day before were the first in Jerusalem since the incursions.

The attack occurred on the eve of the release of a U.N. report into the Israeli military actions in the West Bank town of Jenin in March. The report rejected Palestinian claims that 500 Palestinians were killed, but criticized both sides for putting civilian lives at risk, Western diplomats said in New York.