MANDALAY, Myanmar — Gunmen dressed in soccer uniforms halted an express bus on a main highway in Myanmar’s troubled Rakhine State and kidnapped 31 people, most of them firefighters, the authorities said on Sunday.

The abduction happened Friday morning, and began when a man stepped onto the highway in the bus’s path outside the ancient town of Mrauk U and forced it to stop, according to a military spokesman, Col. Win Zaw Oo.

More than 10 armed men in soccer uniforms, identified as members of a rebel group called the Arakan Army, then emerged from the jungle and boarded the bus, he said. They ordered the passengers to take their belongings and marched them away.

The group has not been seen since. Two bus drivers and an assistant were allowed to leave.

Rakhine State was the main site of the brutal ethnic cleansing of Rohingya Muslims carried out by Myanmar’s military, including a campaign of murder, rape and the burning of villages. Since 2017, more than 700,000 Rohingya have fled across the border into Bangladesh, where they live in squalid refugee camps with little prospect of returning to their homes.