MANILA, Philippines—Suspected extortionists bombed a bus in the restive southern Philippines on Wednesday, killing two passengers and wounding five others, the military said.

The military initially reported 10 dead but regional commander Lt. Col. Benjie Hao later revised the death toll.

The bomb went off on the bus as it pulled into a terminal in Carmen town in North Cotabato province, said another military officer, Col. Leopoldo Galon.

Among the five wounded were two children aged 6 and 11 years, he said.

He said that extortion gangs linked to Muslim rebels have been suspected in previous attacks targeting bus companies in the region.

A bomb at the same terminal in 2010 killed one man and wounded two others, and a month before that, 10 passengers died in a bomb targeting the same bus company.

Muslim rebels and criminal gangs are behind decades-long unrest in the southern Philippines, home to minority Muslims in the predominantly Christian nation.

Hundreds of U.S. troops have been stationed in the south as part of a program to train Filipino troops to fight militants.