MANILA, Sept. 17 (Xinhua) -- At least 15 people died after a truck plunged off a cliff in South Cotabato province in the southern Philippines on Tuesday morning, local police and an official have said.

Police said the truck, with 20 people on board, veered off the road and plunged off a cliff around 10:35 a.m. along a highway in Lamsalome, a village in T'boli town.

Fourteen people died on the spot while several others were injured, police said in its initial report.

However, Rolly Doane Aquino, head of operations in the provincial disaster and risk reduction management office in South Cotabato, said the death toll has already climbed to 15.

"We received reports that one of those injured taken to a hospital already died," Aquino added.

Aquino said the truck was travelling from General Santos City to Surallah town when the accident happened.

Aquino said an investigation in underway to determine the cause of the accident.