Four inmates escaped from the Ludhiana Central Jail on Saturday, police said.
This came to the notice of the jail authorities at the time of attendance in the morning, they said.
The inmates have been identified as Ravi Kumar (24) of Samrala , Suraj Kumar (23) of Sultanpur district in Uttar Pradesh, Aman Kumar alias Deepak (23) of Mandi Govindgarh and Arsh deep Singh alias Deepa (24) of Sangrur, police said.
They scaled the main wall of the jail near the main entrance adjoining the residential flats of the prison staff, they said.
Police have not ruled out the possibility of internal involvement.
It is the first jail break after the CRPF took over the charge of the security of the Ludhiana jail a few months ago.