By Jermont Terry

CHICAGO (CBS) — A woman was taken to the hospital after a man pistol-whipped her on board a CTA Blue Line train Wednesday morning in Bucktown, and police said a man fitting the same description is suspected in another attack.

As CBS 2’s Jermont Terry reported, everyone knows you can’t have guns on Chicago Transit Authority property. There are even signs reminding everyone.

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But on Wednesday night, there was one man not only breaking the law, but even using that weapon to assault people on the ‘L.’

The CTA Blue Line is a busy route. It ushers riders downtown and gets people out to O’Hare International Airport.

But this week, Chicago Police said a man hopped on the ‘L’ to cause some trouble – not to mention harm and scare riders too.

“It’s coming as a shock,” one rider said. “The Blue Line is usually very safe. We ride it all the time.”

Yet, police issued a community alert after what they call a series of aggravated batteries on the ‘L.’

“No, I wasn’t aware of this,” a rider said.

The most recent incident happened just before 9 a.m. Wednesday. We spotted squad cars parked near the Western stop on the O’Hare branch of the line, in Bucktown.

Police said, shortly before 9 a.m., a man riding a northbound Blue Line train struck a 39-year-old woman in the head and arm with a handgun. He then got off the train at the Western stop on the 1900 block of North Western Avenue, and fled the scene.

The woman was taken to AMITA Health Saints Mary and Elizabeth Medical Center Chicago for treatment, and was listed in good condition, police said.

Blue Line service was temporarily suspended between Belmont and Damen for some time after the attack.

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Chicago Police later released surveillance images of the attacker, who also was seen “removing a firearm from his bag and striking CTA passengers in the head” in other attacks on CTA trains.

On Monday morning just before 7 a.m., police said a man fitting the same description attacked another passenger near the platform at the Clinton stop in the West Loop.

The attacks are all random. One man said they “definitely” come as a concern to him as a Blue Line passenger.

“It’s definitely a concern,” he said. “There should never be violence on the CTA.”

Terry asked the man whether he ever sees police officers on the trains when he is on board. He said he never had.

In each attack, the man took off before officers could catch him. The incident near the Bucktown and Logan Square communities on Wednesday left Blue Line riders uneasy.

“The only thing we can do is be alert and report it if we see something,” a woman said.

If you see the man lurking next time you hop on the ‘L,’ you should first get to safety, and then call police.

Chicago Police want to find the man before he attacks anyone else – or worse, uses the gun for pulling the trigger.

“I have confidence the city is going to keep us safe and take care of it,” the first Blue Line rider said.

There is not mention of the man robbing passengers – only assaulting them and then running away.

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Anyone with  information about the incidents is asked to call the Bureau of Detectives – Mass Transit at 312-745-4443. Anonymous tips can be submitted to using reference: RD# JE-325508 & JE-322935.