At least four people were injured after an improvised bomb exploded inside a commuter bus in North Cotabato province in the southern Philippines. The blast occurred at around 1.30 p.m. while the bus, owned by Rural Transit Lines, was traveling on a highway in Kabacan town. “We were traveling and on our way to Tacurong City when the bomb exploded at the rear part of the bus. At least four passengers were injured in the blast,” bus driver Roger Daniel said. He said the bus was carrying more than 30 passengers. It was not immediately known what type of explosive was used in the attack. Early this month, a bomb explosion inside a passenger bus operated by Husky Transit also injured six people in Koronadal City in South Cotabato province. Police blamed the attack to the extortion syndicate called Al-Khobar gang while the military accused the Moro Islamic Liberation Front, the country’s largest Muslim rebel group, as behind the spate of bombings in the troubled south. Former rebels are also known to work as criminals in large parts of Mindanao, demanding illegal taxation or money from bus operators and other businesses in exchange for protection from bomb and other attacks. The MILF, which is fighting for independence, denied all allegations and blamed the attacks on other rebel groups such as the Abu Sayyaf and the Al-Khobar.