MONROE, Washington – An online advertisement offered $28.50 an hour to anyone who wore a blue, long-sleeved shirt, yellow safety vest, eye protection and ventilator mask and waited near a bank.

Apparently, it should have been labeled “decoys wanted.”

Police said a number of people wearing the specified outfit were waiting near a Bank of America branch Tuesday when a similarly dressed man accosted a Brink’s armored truck guard with pepper spray during a cash delivery in Monroe, a town about 25 miles (40 kilometers) northeast of Seattle. Police said the man grabbed a bag of money and eluded pursuers after entering a nearby creek.

FBI agents were trying to determine the source of the ad posted on craiglist.org, which ostensibly was seeking landscaping help on a city project, Monroe police spokeswoman Debbie Willis said.

“We believe the ad was not a credible ad and that it may have been an attempt to get people dressed like the suspect into the area,” she said.

As of Thursday morning no one had been arrested and the source of the ad remained undetermined, FBI Agent Roberta A. Burroughs said.

She told The Herald of Everett that she had never heard of a such a tactic in 15 years of investigating bank holdups.

“There’s nothing about this case that’s run of the mill,” she said.

The amount of money taken was not disclosed. It was not immediately clear how many workers showed up because of the ad.

“The e-mail specifically said to wear a blue shirt and said, ‘If a project manager is not there, do not leave,'” said Mike Stevenson, 30, of Bremerton, one of several prospective workers who gathered at a Monroe park.

“We started wondering if guys were going to show up and shoot paint balls at us, or if we were about to be ‘Punk’d’ and Ashton Kutcher was going to show up,” Stevenson told The Seattle Times, referring to a practical joke television show hosted by the actor. “Turns out we were set up as decoys for a robbery instead.”

A similar ploy was used in the 1999 movie “The Thomas Crown Affair,” in which an art thief wearing a trench coat and bowler hat makes off with a priceless masterpiece as museum security guards are distracted by several lookalikes the crook hired.

Burroughs said the tactic failed to cause similar confusion at the scene Tuesday.

“Was it really necessary? Did it help the guy out? I don’t think so,” she said.