A powerful blast in a crowded restaurant in the southern Philippines has killed six people and wounded dozens, police said.

The improvised explosive device went off around midnight on Friday in the port city of Cagayan de Oro.

The motive for the blast was not immediately clear, local police chief Graciano Mijares said.

"We will have to wait for the results of the investigation," he added.

I looked around and saw this ball of white smoke. People were running away bloodied and survivors were dragging at least seven or eight people away from the blast site.

Noel Arcenas, shop owner

Cagayan de Oro, about 800km south of Manila, is a relatively peaceful city in the Mindanao region where armed Muslim groups, communist rebels and heavily armed crime gangs operate.

"Three people were killed on the spot from the blast," said army spokesperson Lieutenant-Colonel Leo Bongosia, adding three others died in hospitals. "We were shocked. We don't have this kind of attack in years."

The victims of the blast were mostly medical representatives and guests of a pharmaceutical company who had gathered for a medical conference, Mijares said.

Local politician Roldan Lagbas, a member of the provincial executive board of Misamis Oriental province, was also killed.

Noel Arcenas, who owns an electronics shop at the shopping complex where the restaurant is located, said at least 100 people were inside the popular establishment when the explosion occurred.

He said he was standing about 15 meters away when he felt and heard the blast.

"I looked around and saw this ball of white smoke. People were running away bloodied and survivors were dragging at least seven or eight people away from the blast site."

The powerful explosion broke glass panels, upturned tables and chairs, and damaged cars parked up to 30 metres away, reporters at the scene said.

Source: Reuters