QUETTA, Pakistan (AP) — As hundreds of mourners on Saturday protested the killing of 22 people in deadly bus hijackings in western Pakistan, the assaults raised new fears that a long-simmering insurgency there could be growing more violent.

The country’s restive Baluchistan province has seen two major attacks in the span of a month, including an April assault on a dam project that killed at least 20 people and Friday’s bus hijackings. In both, gunmen let Baluch people flee while killing others, signaling a worrying ethnic bent to an insurgency seeking independence for the oil- and mineral-rich region that’s also home to Islamic extremists.

Mureed Baluch, a militant who identifies himself as the spokesman of United Baluch Army, which has attacked security forces in the past, claimed the bus attacks Saturday.

The attacks Friday night, which happened in the province’s mountainous Mastung district, saw gunmen wearing security force uniforms stop the buses, then check ID cards to determine the ethnicity of their captives, one survivor told private satellite news channel Geo TV.

Local Pashtun leader Allah Dad told The Associated Press that the gunmen made Pashtun passengers stand in a line, then shot them dead.

“What was the fault of the Pashtun passengers who were killed in the attack on the buses?” Dad asked. “We want assurance from the government that the attackers will be arrested and they will be punished.”

On Saturday, hundreds of Pashtuns, who make up about 35 percent of Baluchistan’s 9 million residents, placed 16 coffins with the bodies of their dead in front of the governor’s house in the provincial capital, Quetta. The protesters later dispersed peacefully after meeting with Abdul Malik Baluch, the province’s top elected official.

The country’s paramilitary Frontier Corps said Saturday that 200 troops were taking part in an operation to find the gunmen, while Baluchistan Home Minister Sarfaraz Bugti said security forces already killed two of the attackers.

Separatists in Baluchistan, which borders both Afghanistan and Iran, want a substantial share of revenue from gas and mineral resources and complete autonomy from Islamabad. In the mid-2000s, Gen. Pervez Musharraf’s government launched a crackdown on insurgents there, with Baluch and human rights activists say Pakistani forces detained their people for years without bringing them to court, sometimes killing them and dumping their bodies in the desert.

The current violence is the deadliest to target civilians in the region in recent years. Kalim Ullah, a retired history professor who lives in and has extensively studied Baluchistan, said he worries the insurgency may be growing increasingly violent and spark further ethnic tension.

“There is a need to wisely handle the situation following yesterday’s attack on Pashtun people as this is something that is very dangerous,” Ullah said. “The government must take immediate steps to avoid such incidents in future because Baluchistan could plunge into a deep turmoil if Baluch and Pashtun people clashed.”

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Associated Press writer Munir Ahmed in Islamabad contributed to this report.

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