Thieves in the western Indian city of Mumbai robbed a government-owned bank after gaining access via a 25ft (8m) tunnel that they dug over four months.
The police told the BBC that cash and jewellery were stolen but the value of the haul is yet to be determined.
Authorities believe the group rented a space next to the Bank of Baroda so they could dig the tunnel.
They are said to have run a grocery shop on the premises to provide cover for their activities.
The suspected thieves have been missing since the robbery on Saturday night.
It is not clear how the men managed to dig the tunnel for months without arousing suspicion.
Indian media spoke to distraught customers whose safe deposit boxes were robbed. Dagdu Gavani told the Mumbai Mirror: “All my life’s savings were kept in the bank locker. The jewellery, which we had owned since generations, has been lost.”
Employees of the bank, located in a Mumbai suburb, discovered the robbery on Monday morning and alerted the police.
The police told the BBC that 30 of the bank’s 225 safe deposit boxes were robbed.
The suspects are yet to be identified.