About 200 prisoners escaped from a maximum security prison in Indonesia's fourth-largest city, Medan, last night.
The break-out occurred after a protest over a lack of water and electricity turned violent, a police spokesman said.
The spokesman said 15 of the 200 prisoners who escaped were believed to be "terrorists".
The prisoners fled after a fire broke out inside the prison that killed at least two inmates and two prison officials, another police official said.
Soldiers and police officers in Medan, the capital of North Sumatra, have yet to track down many of the escapees.
Local media said the prison held more than 2,500 inmates.
That would put the prison population nearly 150% above its capacity of 1,054.