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MANILA, Aug 3 (Reuters) - Two crude bombs ripped through a bus terminal in southern Philippines on Friday, killing one and wounding an undetermined number, in the second attack in as many months on the station, police said.

Robert Kuinisala, police chief in South Cotabato province, said a man was killed instantly when the first device exploded at about 5:30 p.m. [0930 GMT] at the terminal in Koronadal City.

Minutes later, a second bomb exploded inside a parked commuter bus, Kuinisala added.

"We've sent some people to investigate the explosions," he said, adding a group engaged in extortion activities could be behind the attacks.

"The bus company got telephone calls early in the day from a group called al-Khobar demanding protection money."

On July 7, an improvised bomb exploded at the same terminal in Koronadal City, but no one was hurt because passengers had already left the bus on which the device had been planted.

Police said Friday's twin explosion was the 10th attack on bus terminals since April on the troubled southern island of Mindanao, killing nearly 20 people and wounding close to 50.

The attacks were blamed either on Islamic rebels or groups trying to extort money from bus operators.

"The bus was a total wreck," Miguel Espanol, a passenger who broke an ankle while trying to escape from the first blast, told Reuters, adding that the bus was still on fire.

The Philippines is fighting a long-running Muslim insurgency in the south of the mainly Roman Catholic country. The conflict has killed more than 120,000 people and displaced 2 million.

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