Prime Minister Benjamin Netanyahu said Israel will find the people responsible for Monday’s bombing on a bus in Jerusalem, as investigators continued to piece together the rush-hour attack.

Police did not say if they had any leads on who was responsible for the bombing of the number 12 bus, which wounded 21 people, and no terror group took responsibility for the attack in the immediate aftermath.

Netanyahu said Israeli forces would locate and punish those responsible.

“We will find out who placed the bomb, we will reach those who dispatched them and we will also get to those who stand behind them, and settle the account with these terrorists,” he said.

The prime minister also sent wishes for a speedy recovery to those injured in the bombing.

Two people were seriously injured, including one in critical condition, and six were moderately injured, police and paramedics said. There was no immediate claim of responsibility for the blast by any terrorist groups or individuals.

Firefighters look on as two buses burn in Jerusalem. Police launched an investigation into the incident, April 18, 2016. (Israel Police)

Firefighters look on as two buses burn in Jerusalemm April 18, 2016. (Israel Police)

The bus exploded as it was passing near the Talpiot neighborhood in the southern end of the capital carrying a number of passengers at around 5:45 p.m., police said. The blast set a car and a second empty bus on fire, injuring several more people.

President Reuven Rivlin said Israel would not flag in its fight against terror.

“It is clear to us all that the struggle against terrorism is ceaseless. We will pursue and we will reach all those who wish us harm, until quiet is assured,” he said.

Joint (Arab) List Chairman Ayman Odeh leads the weekly party meeting at the Knesset, October 12, 2015. (Miriam Alster/Flash90)

Joint (Arab) List Chairman Ayman Odeh. (Miriam Alster/Flash90)

Leader of the Joint (Arab) List MK Ayman Odeh denounced the attack, while also accusing Netanyahu of driving the cycle of violence.

“I strongly condemn the explosion this evening in Jerusalem in which many innocent civilians were injured,” Odeh said in a statement. “Harming civilians is unacceptable and it also damages the justified Palestinian campaign to end the occupation.

“The Netanyahu government fuels the bloodshed and is fueled by it,” he continued. “Despair is fertile ground for terrorism. Only a diplomatic solution will bring security for both peoples.”

Israeli police check a burnt-out bus following an explosion in Jerusalem on April 18, 2016. (AFP PHOTO / AHMAD GHARABLI)

Israeli police check a burned-out bus following an explosion in Jerusalem on April 18, 2016. (AFP/Ahmad Gharabli)

The terror attack broke weeks of relative calm in the city after a six-month wave of Palestinian terror and violence seemed to be subsiding, and marked a return to a type of violence not seen in Jerusalem for years.

Jerusalem police chief Yoram Halevi told media the blast was caused by an explosive device placed on the bus, but police did not know if the bomber was on the bus at the time of the blast.

“When a bomb explodes on a bus, it is a terror attack,” Halevi said, confirming that the bombing had been a terrorist action.

Police were investigating whether one of the people seriously injured in the explosion was in fact the terrorist responsible. However, the identity of the burned victim had not yet been confirmed, a spokesperson said.

The driver of the bus, who was lightly injured, told media he checked the bus for bombs twice before starting his route.

Prime Minister Benjamin Netanyahu speaks before an audience of the union of local authorities in Tel Aviv, April 14, 2016. (Screenshot/YouTube)

Prime Minister Benjamin Netanyahu speaks before an audience of the union of local authorities in Tel Aviv, April 14, 2016. (Screenshot: YouTube)

Gaza Strip-based Palestinian terror group Hamas praised the attack but did not claim responsibility in a statement on its website.

“Hamas welcomes the Jerusalem operation, and considers it a natural reaction to Israeli crimes, especially field executions and the desecration of the Al-Aqsa Mosque.”

Other Palestinian groups similarly applauded the bomb attack without claiming any hand in it. The Palestinian Islamic Jihad “welcomed” the bombing as did the Popular Resistance Committees, which also called for more attacks.

The bombing was a stark reminder of an attack method commonly used during last decade’s Second Intifada, but which has since become rare as so-called lone-wolf attackers have assaulted Israelis using simpler weapons, such as knives, guns and cars.

“The pictures this evening raise difficult memories for all of us, and can’t even imagine what the Jerusalemites feel who once again must look at burnt buses,” Zahava Galon, head of the dovish Meretz party, wrote on Facebook. “Against the despicable terrorists who will do everything to destroy our life here needs to stand a brave leader who can broadcast not only strength but also hope for a different future. To my regret, Netanyahu is not even a quarter of that leader.”