Toronto Police are warning the public to be careful when using debit cards in taxis after charging a ring of crooked cabbies with more than 250 counts of fraud and identity theft.

Six people are alleged to have stolen millions of dollars from unsuspecting customers around the GTA in recent years—often without a customer's knowledge.

It all links back to an elaborate (and recurring) scheme involving rigged Point of Sale machines, decoy debit cards, stolen PINS and drained bank accounts.

One man arrested after a taxi debit-card scam. Be vigilant when using debit cards . Maintain possession at all times. pic.twitter.com/scdy0FAXpv

— Toronto Police (@TorontoPolice) September 7, 2017

Here's how it works, according to police:

Drivers pick up a customer in the early morning or evening hours and drive them to their destination. When the customer attempts to pay using debit or credit, they're handed an "altered Point of Sale" machine by the driver.

The customer enters their PIN, at which point the machine returns an error. The driver then asks for the machine back—with the card still in it—to see what's going on. At this point, the driver switches the passenger's actual debit card with someone else's from the same banking institution.

It normally isn't until later that the customers realizes that their PIN was recorded by the fake Point of Sale machine. All a cabbie needs to do is hit up the bank, enter your code, and voila: Your cash is now their cash.

"The customer's funds are depleted from their accounts fraudulently," explains a Toronto Police media release. "The customer usually has no knowledge of the fraud until the bank notifies them, or they attempt to utilize the card provided to them by the driver at a later date, realizing it has been swapped."

This past November, one victim told the CBC that he'd been bilked out of $3,500 by fraudsters. Another victim said he lost $4,100 in one fell swoop.

0117 07:00 Arr Md In Taxi Fare Scams, Four Men, A Woman & A Boy, Fac... Ft Fraud Chgs, https://t.co/H78OPcb7gz

— Toronto Police (@TorontoPolice) January 17, 2019

Police announced on Thursday that four men, one woman and a 16-year-old boy, all from Toronto, had been arrested in connection with the recent bank card thefts. 

They are collectively charged with over 262 counts of fraud-related crimes. The cab companies they worked for were not involved in the scam, say police, and will not be held accountable.

Police do warn, however, that "there are still a number of incidents occurring" and that "there are still outstanding individuals actively defrauding the public utilizing various cabs in the GTA."

Be careful.