By Jermont Terry

CHICAGO (CBS) — Police are searching for a specific car in the race to stop a violent carjacking crew from striking again. A couple of suspected teen carjackers are already under arrest.

Police said the teens were on a busy crime spree spanning six cities.

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An off duty Cicero police detective just happened to spot the car linked to 21 carjackings.

The detective pulled to the side at 49th and Cicero and call police, but the crooks did not give up so easily. 

For weeks a Chrysler Sebring has been on the radar for Cicero police. The older model sedan spray painted black is connected to at least three robberies and one burglary in the town of Cicero this month.  

And a man seen with a gun during one robbery is believed to be the driver. Investigators say he has put some miles on the Sebring. They have linked him and three others to the carjacking and robbery spree.

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According to police, the thieves are connected to 21 carjackings and robberies and less than a month. They took place in Berwyn, River Forest, Central Stickney, Elmwood Park and Oak Lawn.

But on Wednesday in Chicago that off duty Cicero detective who was aware of the crim spree spotted the Sebring near 49th and Cicero. He watched the men drive north, and police say when they got to a Dunkin Donuts at 47th and Cicero, he tried carjacking someone in the parking lot.

But the thieves didn’t know the off duty detective and the Chicago Police Department were right behind the.

Two 18-year-olds took off running. Police arrested them in the Garfield Ridge neighborhood. But the driver and his passenger who carries a knife drove off in that Sebring and have not been found yet.

Police are warning everyone to be on the lookout for the black spray painted Sebring with tinted windows and black painted rims. The car has no front or rear plates.

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They know the duo is desperate, so the hunt is on to find them before they strike again.