Last week Abu Ulbah’s rage may have exploded. Before dawn last Wednesday, the Palestinian left home to drive day laborers across the border into Israel–his third morning back at work since the country lifted its closure of Gaza in late January. At 8 a.m. Abu Ulbah plowed his bus into a crowd of Israeli soldiers at Azur Junction near Tel Aviv, killing eight and injuring 38; he was later wounded and captured after a high-speed chase. It was the worst attack in Israel since late September and plunged the country into yet more grief and anxiety. Many Israeli security experts fear that the driver could represent a new breed of terrorist: apolitical, unaffiliated with militant organizations, yet radicalized. Israeli hard-liners intensified calls for the permanent closure of the West Bank and Gaza. Others warned that imposing a total stranglehold could foster deeper rage–and create an army of Abu Ulbahs.

The attack gave new momentum to incoming Prime Minister Ariel Sharon’s efforts to form a government. Last Friday Ehud Barak, who was trounced by Sharon at the polls two weeks ago, accepted the post of Defense minister and Shimon Peres signed on as foreign minister. That paved the way for a unity government between the Labor and Likud parties. But the smooth transition was overshadowed by fears of new attacks across the region; on Friday afternoon Hizbullah commandos fired an antitank missile from Lebanon into Israel, killing one Israeli soldier. Meanwhile security agents are sure to face questions about their screening procedures for Arab workers inside Israel: NEWSWEEK has learned that weeks before the attack Abu Ulbah sought treatment for his mood swings at a Gaza psychiatric clinic.

Until last week his life was largely uneventful. The youngest of four brothers, Abu Ulbah grew up in Gaza. He and his wife, Menal, and their five children lived in a comfortable apartment in Sheikh Rodwan, a neighborhood of crumbling housing blocks, refuse-strewn streets and walls covered with political graffiti. Hamas militants are known to infest the quarter, yet Abu Ulbah apparently had little contact with them. In 1995, after a lengthy vetting process by Israeli security, he got a coveted job as a bus driver for Egged, Israel’s largest transport company. Ron Ratner, a spokesman for Egged, said Abu Ulbah was an “exemplary employee.”

Abu Ulbah’s life began to fall apart with the outbreak of the intifada last September. The Israeli government sealed the Gaza Strip, and he was suddenly left both unemployed and penniless. To feed his family, Abu Ulbah wheedled rice and vegetables from shopowners on credit and accepted handouts of flour, sugar and cooking oil from his father-in-law. He looked in vain for a job inside Gaza, clinging to the hope that Israel would soon unseal the border. “He called the manager at the Erez border checkpoint daily, asking, ‘When can I go back?’ " recalls his father-in-law.

The months of inactivity buffeted him emotionally. “He would just sit in the bedroom watching TV news and drinking coffee and tea,” his wife says. “He would tell the children, ‘Leave me alone’.” He clashed frequently with his wife, forcing her and their five children to take refuge at her parents’ home. He complained of headaches and admitted that he “didn’t feel well mentally,” his wife says. Over the past two years Abu Ulbah had sporadically taken Prozac, lithium and other drugs. A month before the attack, the driver again sought psychiatric help. According to medical prescriptions kept by Abu Ulbah’s family, the head of the psychiatric department at Gaza Hospital, Dr. Reiad al-Aqra, prescribed heavy doses of Prizma, an anger-control drug; lithium, to combat depression, and Tegratol for nervousness and confusion. (Al-Aqra declined to be interviewed by NEWSWEEK.)

Abu Ulbah finally got some good news two weeks ago. Israel reopened the border on Jan. 22 and began renewing security clearances on a selective basis. In early February “the Egged manager telephoned Khalil and told him he could come back to work,” his father-in-law recalls. “His spirits lifted.” Abu Ulbah got up at 2 o’clock on the morning of Feb. 14, bade his wife goodbye and took a taxi to pick up his bus at the border crossing at Erez. “I saw Khalil at Erez at 4:30,” says an Egged colleague. “He was totally normal.” Three hours later he dropped off the last of 53 passengers, then headed down Route 44 to his lethal rendezvous. It is still unclear whether Abu Ulbah planned the attack or it was a spur-of-the-moment act.

Could anything have been done to stop Abu Ulbah? In an interview, a top Israeli security official defended the screening process that allowed the driver to enter Israel, but admitted that evidence of Abu Ulbah’s psychiatric problems could easily have been missed. “We don’t have access to everything inside Gaza,” he said. Abu Ulbah’s relatives, meanwhile, insist that the deaths were the result of a “traffic accident.” But few of them are grieving for his victims. “I’m happy about it,” says student and family friend Hani, 25, who wouldn’t give his last name. “The killings were a simple way to teach the Israelis a lesson–blood for blood.” As the intifada drags on, that’s a lesson that more and more ordinary Palestinians seem eager to impart. And it is one that Ariel Sharon must absorb.