The next time you pay by debit in a taxi, keep a close eye on your card.

Toronto police warn that a group of cab drivers has been swiping riders' bank cards as they pay — and then driving straight to ATM machines to empty bank accounts before victims even realize what's happened.

Dozens of cab riders have been victimized across the city in recent weeks and the crimes are continuing daily, the lead investigator in the case said Friday.

The number of reports coming into police across the city "has escalated quite a bit" in recent days, Det. Chris Beattie said in an interview with CBC News.

He said it appears that a "small group" of drivers is carrying out the fraud.

Beattie said it's happening primarily to people catching taxis in the downtown core, mostly late at night. But, it is also happening at other hours and in other locations.

"You flag down a cab, they have a point-of-sale machine that's programmed to store the information from your card, they put your card in it, you punch in your PIN numbers, he'll take the machine back, pull out your card and switch it with a fake card from the same bank."

Beattie warns passengers to look carefully at both the debit card and the receipt they get back. The receipts typically say "Toronto Cabs" or "GTA Taxi" at the top, rather than the legitimate name of the company.

Another red flag is that the taxi driver sometimes says he doesn't have change if you try to pay with cash, said Beattie.

He said it is not clear whether those involved are legitimate taxi drivers with major cab companies. Police suggest riders always take note of the company and number of the taxi they catch.

Police got wind of the fraud in mid-December when a TD Bank fraud investigator reported a pattern of 12 incidents in which cab riders saw more than $55,000 taken from their accounts.

A similar scam led to charges in Montreal last year. One victim, Julie Piesina told CBC News how hundreds of dollars disappeared from her account after she paid for a cab with her bank card.

And in the summer of 2014, Peel Regional Police warned of a similar scam happening with both limousines and taxis out of Pearson Airport.