At least three people have lost money over the past few days in an alleged fraud while trying to withdraw money from an ATM of a nationalised bank near Kishore Bharati stadium in Jadavpur.

The victims told police their cards got locked in the ATM slot and did not come out.

When they called a helpline number stuck inside the kiosk, they were told to provide their PINs to unlock their cards, they told the police. Within minutes of sharing the PINs, their money was gone.

The latest victim, Balai Sardar, of Singhabari in Kalikapur off EM Bypass, said he lost around ₹25,000 on Friday night after his card got stuck in an SBI ATM near Kishore Bharati. The ATM, adjoining a bank branch, did not have a guard.

Sardar’s complaint with Survey Park police station led the police to start a probe.

All three complaints have emerged from the same ATM.

The cops said they suspect a gang was targeting unguarded ATMs. More kiosks could be compromised, they said.

Sardar told the police he went to the ATM to withdraw money around 8.30pm on Friday. The card got stuck in the ATM after it was inserted, he told the police.

He called the helpline number available at the kiosk. The person on the other end asked Sardar to follow some instructions to unlock his card, which he did. After returning home, he received text messages saying ₹25,000 had been withdrawn from his account in three instalments, he told the police.

Another victim, Arup Jyoti Pradhan, said he was instructed to use a code to cancel the last transaction using the card stuck in the ATM slot. Then he was told to use his PIN to block the card and meet the bank officials the next day to apply for a new card.

“After I returned home, a series of transactions worth ₹10,000 each were carried out in a flash. The messages just kept coming one after another. I lost around ₹1.3 lakh,” Pradhan told reporters.

Officers suspect that calls to the helpline number went to a person who is part of the gang. Soon after an account holder shared the PIN, the fraudsters withdrew money from the accounts, an officer said.

“It could be that a gang, similar to the Romanian gang that used to operate earlier, has started targeting unguarded ATMs. We will need some time but will reach them,” said a senior officer of Survey Park police station.

In 2019, Kolkata Police busted a “Romanian gang” whose members would allegedly fit skimmers in unguarded ATMs across the city to clone debit card details and withdraw money from the accounts of ATM users.

Cyber security experts suggested avoiding unguarded ATMs. If forced to use one, users should check if the machine’s card slot or keypad were sticky, they said.

In case of a problem, the user should only call the helpline number provided by the bank, an officer said.

If a card gets stuck, block it immediately using internet banking and lodge a complaint with the cyber cell of Kolkata Police and with the national cyber crime reporting portal under the Union ministry of home affairs, the officer said.