Philippine police announced Tuesday that the number of people killed by the bomb explosion on the southern island of Mindanao has risen to eight.

Charles Calima, chief superintendent of the regional police, said on radio dzMM that another two people have died in hospital from wounds they suffered in Monday's explosion on a busy street in Cotabato city.

Calima added that 13 people remain hospitalized following the attack, for which none of the armed groups operating in the region have taken responsibility.

The bomb was concealed in a passenger van parked in front of a shopping mall and the explosion set fire to two businesses, one of them a funeral home, and damaged four vehicles.

The governor of the Autonomous Region in Muslim Mindanao, Mujiv Hataman, said on GMA television that the attack in Cotabato was "unusual" because "there have been explosions here but this is the first time anyone has used a car bomb."

The bomb was detonated just as the armored car of the city administrator, Cynthia Guiani-Sayadi, was driving through the area. In recent weeks the city official has received several death threats, according to GMA.

Armed communist and Islamist groups have operated for decades on Mindanao.

Cotabato, with a population close to 300,000 including both Christians and Muslims, is one of the iconic cities of the Autonomous Region in Muslim Mindanao. EFE