The scene of a bus explosion in Jerusalem on Monday, April 18, 2016. Photo: United Hatzalah Spokesperson’s Office.

At least 21 people were injured on Monday in a rush hour terror attack on a Jerusalem bus, local authorities confirmed.  Shortly afterwards, Israel’s Prime Minister Benjamin Netanyahu vowed to “settle the score” with those responsible for the attack.

The bombing occurred in the late afternoon in Israel as the number 12 bus was driving on the busy Moshe Baram street in Jerusalem’s Talpiot neighborhood, located in the southern end of the capital.

An eyewitness told Israel’s Channel 2 that he heard an explosion before a fire broke out. Although the cause of the incident was initially unclear, Jerusalem Police Chief  Yoram Levy soon confirmed, “There is no doubt that this is a terror attack.”

Jerusalem mayor Nir Barkat told the news station that the explosion was caused by a small device near the back of the bus and called on the public to remain calm.

According to Magen David Adom paramedics, at least two of the wounded are in serious condition, seven are in moderate condition and the remainder are in light condition. Police said that some of the injured were on a nearby bus, which also caught fire. The victims were evacuated to the local Shaare Tzedek medical center and Hadassah Ein Karem hospital in Jerusalem.

Ze’ev Sofer, the director of the ambucycle division of paramedic organization United Hatzalah, was among the first responders at the scene of the attack. “When I arrived at the scene I encountered numerous injured individuals outside of the two buses that were on fire. Due to initial reports of mass casualties, United Hatzalah volunteers arrived at the scene with increased numbers. We treated the injured for burns and other injuries. Among them were two individuals in moderate to serious condition. Damage was caused to vehicles nearby the buses as well,” he said.

While no terrorist group has yet to claim responsibility for the incident, the explosion occurred a few hours after Israel announced it had uncovered and “neutralized” a terror tunnel running from Gaza into Israel. Hamas, which denied responsibility, praised the bus bombing in a statement. “Hamas blesses the Jerusalem operation, and considers it a natural reaction to Israeli crimes, especially field executions and the desecration of Al-Aqsa Mosque,” the group said.

Danny Ayalon, a former Israeli ambassador to the US, denounced the terror attack and called on the international community to do the same. “Terror is terror is terror. I urge the international community to immediately condemn the Jerusalem bus bombing,” he wrote on Twitter.

Watch footage from the scene of the explosion below: