The fire in the prison in Banten province broke out at some time between 1am and 2am on Wednesday morning, a spokesperson for the prison department of the law and human rights ministry said.
“The cause is under investigation,” said Rika Aprianti, adding that inmates were still being evacuated from the jail in Java’s westernmost province, The Guardian reported.
The block housed inmates being held for drug-related offences and had a capacity for 122 people, she said. She did not say how many people were present when the fire broke out, but confirmed the jail was overcrowded.
The prison in Tangerang, an industrial and manufacturing hub near Jakarta, housed more than 2,000 inmates, far more than its 600 people capacity, according to government data as of September.
Kompas TV showed footage of firefighters trying to put out huge flames from the top of a building. The broadcaster reported 41 people had died and 8 had been seriously injured.
“The initial suspicion is this was because of an electrical short circuit,” police spokesperson Yusri Yunus told Metro TV, which cited a police report saying that 73 people also had light injuries.