At least three Vietnamese tourists and an Egyptian tour guide were killed Friday when a roadside bomb struck a tourist bus in Egypt, Prosecutor-General Nabil Sadek announced Friday night , according to state-run Ahram Online.

The bombing took place in the Giza region near Cairo, where the pyramids are located.

At least 11 people were wounded, Sadek said. Authorities said earlier the wounded include 10 Vietnamese tourists and the Egyptian bus driver.

The incident occurred on El-Maryoutiya Street in Giza’s Haram district, where an improvised explosive device was hidden near a wall. The bomb went off when the bus went by, authorities said.

Vietnam’s Foreign Minister and Deputy Prime Minister, Pham Binh Minh said he was “deeply saddened” by Friday’s attack.

“MoFA Vietnam (Vietnam’s Ministry of Foreign Affairs) stays beside victims of the #TourBusAttack & their families, in close coordination with Egyptian Govt on the case,” he wrote on Twitter.

Vietnam’s Foreign Ministry also said on Twitter it has proposed to the Egyptian government that it grant emergency visas to the relatives of the victims.

No one has claimed responsibility.

Egyptian Foreign Ministry spokesman Ahmed Hafez called the attack an act of terrorism.

“The bombing of the tourist bus in El-Maryoutiya, a despicable, cowardly terrorist act which targets what cannot be targeted: The determination of Egypt and the Egyptians,” Hafez wrote on Twitter.

“We extend our sincere condolences to the victims’ families in Vietnam and Egypt. We will continue to move towards a new year of determination to root out terrorism,” he wrote.

Sadek ordered an urgent investigation into the explosion and the urgent completion of autopsy reports for those killed, Ahram Online reported.

He also ordered prosecutors to conduct a forensic investigation of the materials used to make the IED and to collect all surveillance camera footage in the vicinity of the explosion, the news outlet reported.

CNN’s Hossam Ahmed reported from Cairo and Mohammed Tawfeeq reported and wrote from Atlanta. CNN’s Joe Sterling and Hamdi Alkhshali contributed to this report.