MUZAFFARABAD, Pakistan (AP) — Eighteen inmates, including some on death row, have escaped from a prison in the disputed Himalayan region of Kashmir after overpowering a guard with a pistol, Pakistani officials said on Monday.

Local police chief Riaz Mughal said one of the prisoners was shot and killed in the breakout from Rawalakot prison the previous day.

A massive search has been launched to trace and arrest all those inmates who fled the prison, Mughal said, authorities opened an investigation into what lead up to the prison break. The prison's chief and some other officers have already been dismissed from their post while some officials had been arrested for question, he said.

Mughal said six of the prisoners were on death row, while another three were serving life sentences. Such jail breaks are rare in Pakistan, he said.

Officials say one of the inmates had a pistol that was used to overpower a guard and snatch the keys to the prison cells.

The disputed Himalayan region is divided between India and Pakistan, both armed with nuclear weapons. The South Asian neighbors have fought three wars since their independence from British colonial rule in 1947.