Transcript for Phone Scam Caught on Tape
An urgent warning about a phone scam claiming countless victims. Criminals pretending to be irs agents asking you to send them money. So far they have collected millions. ABC's Clayton Sandell got one of those fake irs agents on the phone. Here's what we found out. Reporter: The irs agents calling are fake but costing people real money. One victim in particular lost over $6,000. Reporter: Authorities urgent warning this week. Criminals using phone Numbers that make it appear they're calling from the irs telling victims they owe back taxes. We decided to give the scammers a call on a number left on a victim's voice mail. This is what they sound like. Am I in trouble with the irs? Yes, sir. We found the amount you paid in 2011/12 was not the correct amount. So you owe $1,498.37 to the irs. They want me to load nearly $1,500 on a card like this. But the moment I give them this number, all my money belongs to the scammer. Things get hostile. If you're going to hang up the line, I'm going to proceed you to the sheriff's office and within the next hour they will handcuff you and put you behind bars. Reporter: The irs estimates threats like this tricked more than 1,000 victims out of $5 million. It's bogus. The irs needs to contact you. The tack -- taxpayer. You're going to get a letter in the mail first. Reporter: I decide to question their credentials. You're an irs agent, right? Why are you asking me this question again and again. Reporter: They hang up which is exactly what the real irs wants you to do. Clayton Sandell, ABC news, Denver.
This transcript has been automatically generated and may not be 100% accurate.