A powerful bomb which was heard for kilometres killed six people yesterday in a southern Philippine city where the United States and other governments earlier warned of a terror threat.
The explosive device was placed on a vehicle -- either a motorcycle or a van -- parked on a busy road near a hospital during the afternoon rush hour, said city police chief Senior Superintendent Rolen Balquin.
Cotabato photographer Mark Navales described a blood-spattered road strewn with charred bodies and smouldering vehicle parts.
"I saw three mangled human remains, one of them burnt," he told AFP.
"I have never before seen (the effects of) such a powerful blast in Cotabato."
It was the second bombing to hit Mindanao island in 10 days.
A powerful blast at a restaurant packed with doctors and pharmaceutical salesmen left eight people dead in the city of Cagayan de Oro on July 26.
It was not immediately clear whether the two bombings were linked.
At least 26 others were wounded in Monday's attack, although no group immediately claimed responsibility, Balquin said.
Those killed were motorists passing along Sinsuat Street, the main highway in Cotabato that is lined by commercial establishments.
Among the injured were police officers in a vehicle passing through the area, he said.
The bomb went off as a bulletproof car carrying city administrator Cynthia Gulani-Sayadi was passing by. She escaped unhurt, but two bodyguards following her in a separate van were among the dead.
The attack came a month after the United States, Australia and Canada warned its diplomatic staff against travelling to Cotabato and two other southern cities on Mindanao -- Zamboanga and Davao -- over fresh threats of terrorism.
The nature of the threat was not specified but related to "terrorist and insurgent activities", the US embassy had said.
Muslim insurgents have waged a decades-old rebellion on the island that has claimed an estimated 150,000 lives, but the main rebel group is now talking peace with the government.