PUEBLO, Colo. -

A string of counterfeit bills is circulating in Pueblo. Police want people to check their money and make sure they don't have any fake bills. Police say it's not just big bills that are being duplicated.

"The last couple of years we've seen an increase of bogus bills," said Sgt. Mark Duran.

Two weeks ago Bowlero Lanes received a fake $20. A cashier fed it into the register, going unnoticed that night.

"We didn't find out until the bank told us," said Aaron Trujillo, general manager of Bowlero Lanes.

Police say most of the fake bills going around Pueblo are $20 bills.

"Don't just be suspicious on the large-denomination bills," Sgt. Duran said.

Crooks are targeting everything from fast food chains and restaurants to grocery stores and bowling alleys.

Sgt. Duran said, "We're seeing a lot of the smaller bills that are easily passed and not checked."

One easy way to check for a fake bill is to look for a watermark image on the bill.

"You need to look at these bills," said Sgt Duran. "Compare them to some that you already have and look for some of the security features, the security strip on most of the bills, look for watermarks, discolorations."

It's business as usual at Bowlero Lanes, but some things are moving slower.

"People when they come down, want to be waited on right away and I understand that, but we will now have to take the time to check out each bill individually," Trujillo said.

Police say they have arrested two people for passing counterfeit bills. If someone has a bogus bill, report it to police.