The bomb exploded at lunchtime in the university's Frank Sinatra cafeteria. Though classes are not in session, the cafeteria was filled with students who were at the university to take exams.

Witnesses initially said a homicide bomber was responsible, but Israeli police later said the bomb most likely had been planted, possibly in a bag.

"We're talking about an explosive device, apparently not a suicide bomber. It is being checked," said Jerusalem's Deputy Police Chief Ilan Franco.

Hamas' military wing, the Izzedine al-Qassam Brigades, said in a statement released to the Arabic satellite television network al-Jazeera that it had placed a bomb in the cafeteria two hours before the explosion.

Sheik Ahmed Yassin, Hamas' spiritual leader, said the bombing was revenge for Israel's air strike in Gaza last week that killed Hamas military commander Salah Shehadeh and 14 civilians, including nine children

Another Hamas leader, Abdel Aziz Rantisi, said, "Now [the Israelis] are paying the price of killing our children, women and leaders."

At the university, witnesses described a scene of horror and destruction as rescue workers tended to the wounded and bomb-sniffing dogs checked for more explosives.

"I ran in, there were people lying around wailing, covered in blood. Scenes that are indescribable, clothes and flesh torn apart," said Alastair Goldrein, 19, from Liverpool, England.

"I was on my way to lunch," said Goldrein, who has been taking Jewish studies at the university for the past year. "There was a huge, huge explosion. Everything shook and then there was this deathly silence."

"It was packed," Israeli government spokesman Danny Seaman said of the cafeteria. "The place is devastated inside. It's a terrible scene. There are body parts scattered 100 to 200 yards."

A university employee, identified only as Ilana, told Israel Radio that she was leaving the cafeteria when "I heard a very loud explosion. All the glass broke onto the floor and there was darkness and silence. Slowly, people began to leave and other people were lying on the floor."

Goldrein said the cafeteria was a place where students of various backgrounds mixed freely. Many foreign students currently at the university are from Britain and France, he said.

Most of the students are Jewish, though a large number of Arabs also attend the university. Israel's Channel 2 television said Arab students were believed to be among the casualties.

Dr. Ovadia Shemesh, deputy director of Shaare Zedek Medical Center, told the Israeli newspaper Haaretz that most of the wounded were between the ages of 18 and 30.

In Washington, presidential spokesman Ari Fleischer called the bombing "a horrific attack of terror."

"Campuses around the world are places of learning, should be places of peace," Fleischer said. "This terrorist attack underscores again the need for the Palestinian people and Palestinian leadership to take action to halt terrorism so peace has a chance in Middle East."

The White House remarks came as President Bush prepared for two days of talks beginning Thursday to review Mideast peace proposals with Jordan's King Abdullah. The monarch hopes to persuade the Bush administration to step up its timetable for Palestinian statehood and for Israeli withdrawal from the West Bank and Gaza.

The Palestinian Authority, led by Yasser Arafat, said in a statement that it "absolutely condemns the attack against Hebrew University."

However, the Palestinian leadership also said it "considers Israeli Prime Minister Ariel Sharon responsible for this cycle of terror."

An official in Sharon's office, David Baker, said, "Israel is fighting a pitched battle against terror and for the right to walk down the street, take a bus or sit in a cafeteria without the fear of being decimated by Palestinian terrorism."

The university has extremely heavy security. Students said their backpacks are always checked thoroughly by guards at all the entrances.

However, the deputy editor of the university newspaper said the perimeter fence was easy to cross. He said that in April the newspaper had predicted just the type of attack that was carried out Wednesday.

The bombing took place at the Mount Scopus campus of the university, located near the border between traditionally Arab east Jerusalem and west Jerusalem.

"This was one place that I thought was safe," one witness told Haaretz, but another complained that "the security is not thorough — they check your bag and that's it."

Wednesday's blast came a day after a Palestinian suicide bomber blew himself up at a food stand in Jerusalem, killing himself and wounding several Israelis.

Palestinian homicide bombers have carried out more than 70 attacks, killing more than 250 Israelis, in the current round of Mideast fighting. Jerusalem has been hit more than any other city.

Just before the attack, Arafat held a joint news conference with the Rev. Jesse Jackson. Arafat said Palestinian authorities were "continuing our efforts, and will continue, from every aspect, to stop the violence."

Jackson was to go to Gaza to meet with Yassin after seeing Arafat, but the visit was canceled after the bombing. Hamas officials said Jackson called off the trip.

The Associated Press contributed to this report.

http://www.foxnews.com/story/0,2933,59185,00.html