At least 20 people were injured, two seriously, when a bomb exploded on a bus in Jerusalem on Monday. The Shin Bet security service confirmed that the incident was a terror attack.

Prime Minister Benjamin Netanyahu vowed to “reach the perpetrators and those who support them, and ensure those who stand behind it are held accountable.” He also sent wishes “for a speedy recovery to all those who were wounded.”

The blast occurred at about 5:50 P.M. on Moshe Baram Street, near Hebron Road, in southwest Jerusalem. It is the first bombing attack in Jerusalem since the second intifada ended in 2005.

An explosion tore through the bus on the number 12 line, which then set another bus – which was empty at the time – on fire. A Jerusalem Police spokesperson said that most of those hurt by the blast were passengers on the No.12 bus.

“Based on a professional investigation by police demolitions experts, it appears that a bomb went off in the back of the bus, which caused injuries to passengers and the bus to catch fire. In addition, another bus and a private vehicle nearby were also damaged,” the spokesperson said.

Jerusalem police chief Yoram Halevy said the police were in the initial stages of their investigation. “We are checking to find out where the explosive device came from and who placed it on the bus. We do not know of any specific warning about the bomb. All possibilities are being examined,” Halevy added.

Mickey Cohen, the head of United Hazolah emergency responders in Jerusalem, said from the scene, “When I arrived, I saw two buses going up in flames and about 10 casualties among them ... Together with other volunteers from the motorcycle unit of United Hazolah, we provided initial medical treatment to the wounded.”

United Hazolah emergency responders were quick to suspect an explosive device caused the explosion. Glass pieces flew and the fire ignited quickly and strongly, events which were characteristic of a bomb, they said. Jerusalem Mayor Nir Barkat was the first to confirm that it was a terror attack.

Magen David Adom medics evacuated 21 people to Shaare Zedek Medical Center and Hadassah University Hospital in the city.

Ten casualties are currently at Hadassah’s Ein Karem hospital, including four in moderate-to-serious condition; three people who have been sedated and put on respirators; and three were treated for light wounds.

Another 10 wounded are at Shaare Zedek, including one in serious condition with wounds to his limbs and burns all over his body; two in moderate condition, both of whom underwent operations during the evening. Seven others were being treated for light wounds.

Immediately after the incident, many forces were rushed to the scene and an intensive police investigation was launched alongside rescue efforts to help the injured.

In the field, assessments were made by Halevy, professional teams were sent as reinforcements, and the 100 emergency line was also reinforced. The police asked the public to report any extraordinary incidents.

Many police and Border Police forces were deployed across the city in order to maintain security and ensure a quick response to any call.

“Our prayers go out for a speedy recovery for the terrorist attack victims undergoing treatment at this moment at hospitals in Jerusalem,” President Reuven Rivlin said last night.

“On such a day where morning exposes – to the credit of devoted security forces – a terrorist tunnel in the south of the country, and in the evening we ferry civilians returning from their daily routine to hospitals, it is clear to us all that our struggle against terrorism will never stop. We will chase down and reach all those who bid us harm until we achieve quiet,” he added.

Joint Arab List leader Ayman Odeh “utterly condemned” the attack. The Knesset member called civilian casualties unacceptable, saying that they are detrimental to the just Palestinian struggle aimed at ending the occupation.

Odeh added that the Netanyahu government is fueling the cycle of bloodshed, saying that despair proves fertile ground for terror.

Palestinian militant groups, meanwhile, welcomed the attack. Hamas called it a “natural response to the crimes of occupation,” but did not claim responsibility. Islamic Jihad, meanwhile, also welcomed the attack as “proof of the failure of security coordination” between Israel and the Palestinian Authority,” and the Popular Front for the Liberation of Palestine said it “welcomes the operation as a positive and important development of the intifada.”