An unidentified thief dug a 5-feet-long and 4-feet-deep tunnel and barged into a Canara bank branch in the early hours of Thursday, although his heist attempt failed as he could not open the safe of the bank located in Lakhuwas village in Sohna block, police said said on Friday.

The incident came to light on Thursday morning when the employees entered into the branch of Canara bank and found the opening of the tunnel inside the bank. They immediately informed the police about the incident, police said.

It was dug from the back side wall of the bank. The entire incident was captured in the CCTV cameras installed inside the bank, they added.

"The thief entered into the branch but could not open the safe despite efforts, so the cash remained safe. Also the bank alarms start hooting which compell the thief to fled the spot," Preet Pal Sangwan, ACP (crime) said, adding that the efforts were being made to identify the culprit based on the CCTV footage.

The bank employees told the police that this tunnel was dug to the record room.

"A thief was seen walking in the record room in the CCTV cameras. He entered the record room of the bank from the tunnel at around  3.15 am. However, the thief did not find the cash there and returned," said a bank employee on requesting anonymity.

"In connection with the incident a case was registered against an unknown person at the Sohna City police station on a complaint filed by the bank management. Further investigation is underway," Sangwan said.