Indonesian authorities have arrested three people suspected of negligence after a fire ripped through a makeshift factory in North Sumatra, killing 30 people, a police spokesman said on Sunday.

Axar.az reports citing Reuters.

The blaze broke out on Friday in the facility located in a residential area, killing the workers, mostly women. Several children were among the victims, suspected to be the offspring of the workers.

North Sumatra police spokesman Tatan Dirsan Atmadja said two men and a woman, co-owners of the factory, had been arrested and named suspects in the case for negligence causing injury or death.

The suspects could face up to five years in jail if found guilty, Atmadja said.

The fire started when a worker was testing a spark wheel which turned out to be faulty and caused large spark which quickly set ablaze a nearby gas cannister and other flammable materials, he said.

Workers were unable to escape the premises as a gate was locked when the fire started. The supervisor, who was in charge of locking and unlocking the gate, was also killed in the fire, Atmadja added.

Indonesia has a patchy industrial safety record. In 2017, a series of explosions and a fire killed 47 workers and injured dozens at a fireworks factory on the outskirts of Jakarta.