A group of armed men in police uniform on Sunday attacked the Nabha Jail in Patiala and fled with five prisoners, including Khalistan Liberation Front chief Harminder Mintoo.
Police said a group of youths dressed in police uniform stormed the jail and opened indiscriminate fire at the high-security jail.
Five prisoners, including a hardcore terrorist escaped, they said.
Those who escaped include gangster Vicky Gondar, Gurpreet Sekhon, Nita Deol, Vikramjeet, and terrorist Mintoo, police said.
Mintoo was arrested by Punjab Police from Delhi's IGI Airport in 201 in connection with 10 cases, including the 2008 attack on Sirsa-based Dera Sacha Sauda chief Gurmeet Ram Rahim Singh and recovery of explosives at Halwara Air Force station in 2010.