QUETTA, Pakistan (AP) – Train bombings killed two people in restive southwestern Pakistan on Friday, a day after a fierce battle between government and renegade tribal forces left at least eight soldiers and about 20 tribesmen dead, officials said.

The bombs, planted in toilets on trains traveling the main railway line in Baluchistan province, went off within about three hours of each other. Eight other people were wounded.

Authorities’ suspicions were likely to fall on ethnic Baluch nationalists. A low-level insurgency has gathered steam in the impoverished province this year, along with tribal demands for more royalties from the country’s main natural gas fields located on their territory.

Railway police said the first bomb killed a soldier on a train traveling from the provincial capital Quetta to the eastern city of Lahore at a station about 20 miles southeast of Quetta. At least five other people were injured, two critically.

The second bomb went off on a train traveling in the opposite direction about 60 miles southeast of Quetta, killing one person and wounding three.

Tensions in the region escalated Thursday when tribesmen ambushed a troop convoy and fired rockets at a military base on the outskirts of Dera Bugti, 185 miles southeast of Quetta.

The ensuing battle, in which the army deployed helicopter gunships, lasted 16 hours, ending early Friday after the two sides agreed on a cease-fire, said a Frontier Corps spokesman, Lt. Col. Rizwan Malik. He said eight soldiers were killed and 23 injured.

Maj. Gen. Shujaat Dar, head of the corps, told The Associated Press late Friday that between 18 to 20 people from the Bugti tribe – the main tribe in the Dera Bugti area – had reportedly died, and others were injured. He gave no other details.

Hundreds of supporters from ethnic Baluch nationalist parties on Friday protested outside the provincial assembly in Quetta against what they said were high civilian casualties from Thursday’s clashes.

Sardar Akhtar Mengal, an opposition politician and former Baluchistan chief minister, claimed the army killed more than 50 innocent people, including women, children and minority Hindus. He accused the government of concealing civilian deaths.

Dera Bugti lies about 30 miles from Pakistan’s main gas field at Sui, where the military has deployed thousands of soldiers and set up a garrison since rocket attacks killed eight people in early January and disrupted gas supplies across the country.

A parliamentary committee has been set up to examine the tribesmen’s claims for greater royalties from the gas reserves and their other grievances. It is expected to make recommendations to the government soon.