Members of the United Nations Security Council unanimously condemned on Thursday the deadly terrorist attack on a bus carrying Israeli tourists in Bulgaria.

“Terrorism in all its forms and manifestations is one of the most serious threats to international peace and security. All acts of terrorism are criminal and unjustifiable, no matter the motives for them, where, when and by whom they are carried out,” a statement by the Security Council said.

“The perpetrators and organizers, as well as those who finance such reprehensible acts of terrorism must be brought to justice,” added the statement.

The Middle East Quartet – the UN, the European Union, Russia and the United States – also condemned the attack, saying it “is an act of cowardice against innocent people, including children.”

“The members of the Quartet look forward to the apprehension of the perpetrators and their being brought to justice,” the statement posted on the UN’s website said, adding that the Quartet supports all international efforts to assist the Bulgarian authorities and others in this effort.

The Quartet also offered its condolences and sympathies to the families and friends of the Israelis and others killed or injured in the attack, as well as to the people of Bulgaria.

“This attack provides a reminder of the need for the members of the international community to stand side-by-side in the effort to prevent terrorism wherever it may be practiced,” the group’s members said. “The Quartet will continue its effort to reach comprehensive, just and lasting settlement in the Middle East, where all the people will live in peace and security.”

Earlier on Thursday, the names of the five Israelis who were killed in the terror attack were cleared for publication.

The dead are Yitzchak Kolangi, 28, of Petach Tikva; Amir Menashe, 28, of Petach Tikva; Maor Harush, 25, of Akko; Elior Preis, 26, of Akko; and Kochava Shriki, 44, of Rishon LeTzion.

UN Secretary-General Ban Ki-moon issued a condemnation through his spokesperson of Wednesday’s suicide terrorist attack, though he only referred to the “deadly bombing of Israelis” and did not use the word “terrorism.”

U.S. President Barack Obama also strongly condemned the terror attack, saying, “The United States will stand with our allies, and provide whatever assistance is necessary to identify and bring to justice the perpetrators of this attack.”