Shortly before 6 p.m. on Monday, a bomb went off on a bus in Jerusalem, triggering bad memories for many Israelis. This type of attack had not happened in recent years.
Blocks away from the explosion, people paced the sidewalks, talking on cellphones or watching the small screens for flashes of information about what happened. They saw black smoke twist into the sky and heard ongoing sirens as medics, police and soldiers raced to the scene.
Twenty-one people were injured in the explosion, including a 19-year-old Palestinian man, Abdel Hamid Abu Srour. He died the next day, the only fatality from the bombing. Israeli officials say Abu Srour carried the bomb onto the bus, and they dubbed this a suicide bombing.
It's still not clear whether suicide was indeed his intent, but that may matter less for Israeli security than whether he acted alone.
The individual bomber is "not so important" says Barak Ben-Zur, a counter-terrorism expert at Israel's Interdisciplinary Center and a former top official with Israel's internal security agency.
"It's important if someone is standing in background and using young people for those attacks," Ben-Zur says.
Terrorist organizations often have the expertise and resources to carry out more devastating attacks than individuals acting alone, he says.
As of Saturday, six Israelis remained hospitalized, including several who are still unconscious and using respirators to breathe. One is a 15-year-old girl, whose mother was also injured in the bus bombing. A hospital spokeswoman said the mother was treated and released but was staying at the hospital much of the time, to be by her daughter's side.
Israel has focused its investigation on the militant Palestinian group Hamas, which controls the Gaza Strip but has support in the West Bank as well. Israeli police say security forces arrested an unspecified number of Hamas members in the days after the attack.
Shortly after the explosion, Hamas issued a statement claiming Abu Srour was a member of the group. Hamas also praised the bombing, but stopped short of claiming responsibility.
At a gathering in a family home in Bethlehem to mourn and honor Abu Srour, his mother, Azhar Abu Srour, 43, sat on a couch on the front porch, her dark hair drawn back and her face pale. Relatives poured tiny cups of coffee and offered candies from a large basket.
Azhar Abu Srour said she didn't think her son had joined Hamas. But she volunteered that he always admired a Hamas bomb maker, Yahya Ayyash, nicknamed "The Engineer," and revered among some Palestinians for his role in a series of major bomb attacks against Israelis decades ago.
"Every young man has a model and my son took Yahya Ayyash as a model because he hurt those Israelis who hurt us every day," she said.
Israel assassinated Ayyash in a dramatic move in 1996, using an informant and an exploding cellphone. That was before Abdel Hamid Abu Srour was born.
His mother also said her father — her son's namesake — had been killed by the Israeli military in Lebanon in 1981.
He "always felt he should take revenge for his grandfather's death," Abu Srour's mother said.
Still, she wonders if her son meant to die. He was studying hard to pass a chemistry class, his last requirement before college.
Yoram Schweitzer, head of the Terrorism and Low-Intensity Conflict program at Israel's Institute for National Security Studies, says if this was a suicide bombing, it wasn't anything like the wave of suicide attacks Israel experienced during the second intifada in the early 2000s.
"Even if it was a suicide bombing, it wasn't a very successful suicide bombing on the part of the terrorist plans," Schweitzer said. "From the Israeli perspective it's one among several attempts that's been carried out in recent months to do some suicide attacks."
Most of the Palestinian attacks against Israelis during the wave of violence that erupted last October appear to have been carried out by individuals. The majority have been stabbings, although Palestinians have also used guns and cars in attacks. But the Israeli military says in recent months it's uncovered Palestinian cells planning suicide attacks.
Schweitzer says it's crucial to understand the details of Monday's attack to stop future terrorism.
"If we have a case of a lone perpetrator who tried to carry out suicide attacks and was willing to blow himself up with his own capability to build a bomb, then it's something that we need to expect and look for in order to prevent it."
If an organization is involved, Schweitzer says, there's the potential for future attacks that will be "much more fatal."
SCOTT SIMON, HOST:
Israeli security forces are trying to unravel the significance of a bus bombing in Jerusalem this week. That attack wounded about 20 people, including a Palestinian, who later died. Police concluded he was a suicide bomber. Now they're trying to determine whether he was acting mainly on his own or whether Israel could face an organized wave of bombings, as it's seen in years past. NPR's Emily Harris reports.
UNIDENTIFIED MAN: (Chanting in Arabic).
EMILY HARRIS, BYLINE: The song of Muslim prayers filled a living room furnished with ruffled curtains and overstuffed couches in Bethlehem on Thursday. Here, Palestinian women gather to honor the death of Abdel Hamid Abu Sror, the 19-year-old old man who Israeli officials say carried the bomb onto Jerusalem's number 12 bus. The militant Islamist group Hamas also declared Sror the bomber and claimed him as one of their own.
Outside, on the shady front veranda, his mother, Azhar Abu Sror says she doesn't think her son joined Hamas. But she volunteers that he always admired a Hamas bomb maker, Yahya Ayash. Israel assassinated Ayash with an exploding cell phone in 1996, before her son was born.
AZHAR ABU SROR: (Through interpreter) Every young man has a model, and my son took Yahya Ayash as a model because he hurt those Israelis who hurt us every day. Keep in mind also that my father was killed by Israelis. My son is named after him and always felt he should take revenge for his grandfather's death.
HARRIS: Sror is the only one who died in this bus attack. The bomb scene reminded veteran Israeli responder Daniel Katzenstein of much more lethal bombings in the early 2000s, during the second intifada.
DANIEL KATZENSTEIN: The smell, the sights are similar to - thank God it hasn't been as bad as it was then in the, you know, second intifada. But our operations unit is also gearing us up for what type of protective measures we can have.
HARRIS: Israeli counterterrorism expert Yoram Schweitzer notes the thick, black smoke rising over Jerusalem and the photos of wounded people next to charred city buses triggered emotional memories among Israelis about the fear and damage suicide bombers can create. But he says this attack was nothing like that.
YORAM SCHWEITZER: Even if it was a suicide bombing, it wasn't a very successful suicide bombing on the part of the terrorist plan. The Israelis suspect this is one among several attempts that were carried out in recent months.
HARRIS: Other suicide bomb plans were stopped before they happened. Schweitzer says from a security perspective, the main thing about Monday's attack is that forces didn't find this bomber in time. Immediately afterward, Israeli forces arrested a number of Palestinians. Barak Ben-Zur, a former top official with Israeli internal security, says what's most important to find out is whether an organization was behind the young Palestinian bomber.
BARAK BEN-ZUR: It's not so important to individuals that is used for this purpose. It's important if someone's standing in the background and using those young people for those attacks
HARRIS: Terrorist organizations can usually build bigger bombs, he says. But even this relatively small explosion has left several Israelis still hospitalized, some unconscious and on ventilators. One is a teenage girl whose mother was also injured in the bus bombing. The mother was treated and released, but a hospital spokesperson says she's still there most of the time, by her daughter's side. Emily Harris, NPR News, Jerusalem. Transcript provided by NPR, Copyright NPR.