Dhaka, Sept. 27 -- At least 12 people have been killed and around 35 injured after a suicide bomber attacked a police checkpoint in northwestern Pakistan, with gunmen later opening fire on an ambulance carrying victims of the blast to a hospital, officials said.

The ambulance attack killed a rescue worker and injured two others, Nikkei Asia reports citing officials.

The bombing took place on Saturday in Dera Ismail Khan district of Khyber Pakhtunkhwa province, where an explosives-laden vehicle was detonated at a roadside police checkpoint, said Bilal Faizi, a spokesman for the provincial emergency service.

Local police chief Safdar Baloch said most of those killed and injured were security personnel and passersby.

The blast destroyed ...