An armored truck is stolen in a Chicago Heights store parking lot

Chicago Heights, Illinois (CBS) –It’s a dangerous trend – armored truck robberies are increasing.

But the ambush in Chicago Heights on Tuesday ended differently than the robbers expected — with one of them being hit by the truck they were targeting.

The robbery happened in the parking lot of the store at 1333 Western Ave. In the southern suburb. As CBS 2’s Sarah Maci reported, Food 4 Less was back open Tuesday night after the violent attack that occurred in the early afternoon.

Key evidence was lying around the parking lot late Tuesday, where investigators dropped off a clue marker on a shell casing. There were also rolls of coins on the asphalt, and a Loomis armored truck was parked at the scene with its front wheel missing.

The FBI said hours ago that three men in their twenties robbed the armored truck at gunpoint. In a turn of events captured on video, one of the suspects was struck by the armored truck during the operation, and they may have been injured, the FBI said.

The armored truck also struck the suspect vehicle, a dark-colored Nissan sedan, sustaining severe damage to its rear passenger-side door.

It was not clear who was driving the truck in the video, but investigators from the FBI and Chicago Heights Police shared the video — and offered $20,000 — to combat the rising armed robbery numbers.

“You’re right about armed robberies increasing, yes,” said Arthur Loriggio, a professor of psychology and criminology at Loyola University Chicago. “In Chicago, yes. And apparently nationally, yes.”

Lorigio profiles the armed robbers.

“Armed robberies can result in aggravated battery, attempted murder, and murder, so you have to expect that the perpetrator of an armed robbery will be able to shoot the person being robbed,” he said.

We showed you how daring and dangerous these robberies are.

in Aprilthree armored trucks were held at gunpoint — a few hours apart — in Chicago’s Bridgeport neighborhood and in the south suburbs.

in Marcha suspected thief took bags and fled from a Brinks truck in Orland Park.

And in Februaryan armored car guard was shot and wearing a bulletproof vest in Chatham.

Each completed ambush could serve as inspiration for future attacks, Loriggio said.

“If they get away with this type of activity or get away with it, it may encourage others who are willing to do it,” he added.

But video showing a burglar injured during the incident, as was the case Tuesday in Chicago Heights, is unlikely to have as much power as a deterrent.

The FBI said the robbers’ getaway car had no license plates, but had a dealer advertisement with a star and blue letters.

Anyone with information should report tips to the FBI at (312) 421-6700, or to tips.fbi.gov.