YANGON, Myanmar — A bomb exploded Wednesday in a bank in the northern city of Lashio, a region where there is fighting between the government and ethnic minority guerrillas, killing two people and injuring 21 others, Myanmar authorities said.

The Facebook page of army commander Senior Gen. Min Aung Hlaing said officials were investigating whether a terrorist group was behind the explosion. Several ethnic rebel groups are active in northern Shan state, whose capital is Lashio, and those that have not signed a cease-fire with the government are often described as terrorists.

The general’s page identified the two fatalities as female employees of the Yoma Bank branch where the blast occurred.

Military explosive experts, medics, local police and Red Cross workers rushed to the bank after the explosion, which occurred as it was closing for the day. Photos posted by the Information Ministry and on private social media accounts showed considerable damage to the bank, at two entrances. Vehicles parked outside also suffered damage.

Lashio, a major trading town, is 900 kilometers (560 miles) northeast of Myanmar’s biggest city, Yangon, and about 140 kilometers (85 miles) south of an active combat zone. The groups battling the government there include the Ta’ang National Liberation Army, representing the minority also known as the Palaung, and the Kokang minority’s National Democratic Alliance Army.

Myanmar’s ethnic minorities, located mostly in border regions, have been battling the central government for more autonomy for decades.

Myanmar news reports last year said letters purporting to be from the Ta’ang National Liberation Army sought to extort money from hotels in Lashio as part of a protection racket, but the group denied responsibility.