CHICAGO (CBS) — Security concerns were mounting this New Year’s Day after a series of robberies and attacks in the CTA Red Line subway in and around the downtown area.

As CBS 2’s Tara Molina reported Wednesday night, the attacks have happened on trains and platforms in the subway running right under State Street.

The attacks this week are part of an uptick since Thanksgiving, but Chicago Police said they have upped their patrols and arrested one of the suspects behind them.

Hundreds of thousands ride the CTA ‘L’ system daily – more than 759,000, according to the Chicago Transit Authority.

But five of those riders made headlines since Sunday – along a busy and high-profile two-mile stretch of the underground Red Line from Chicago Avenue to Roosevelt Road.

It started Sunday. Just before 7 p.m., a pregnant woman told police that she and a friend were attacked by a group on a train, near the Roosevelt stop.

The 28-year-old woman told officers that she and her friend, a 23-year-old woman, were on the train near the Roosevelt stop when a mixed-gender group of assailant got on.

One female assailant got into a quarrel with the older woman, while a second assailant hit the woman in the back of the head and caused her to fall, police said. The assailants kicked and stomped on the woman’s back and rib area, and then ran off, police said.

The victim was taken to Mercy Hospital with bruised ribs. She also said some of her personal belongings were missing, police said.

At 11:40 p.m., about 10 blocks north at the Lake Street station, a 61-year-old man was attacked by a mixed-gender group of six to 10 attackers who he said followed him onto the platform after harassing him on a train.

Then the entire group attacked, punching the 61-year-old repeatedly and stealing his bag.

A 21-year-old man saw this happening and tried to help, but the group beat him up, too, and stole his cell phone.

The attackers ran off. The victims were taken to Northwestern Memorial Hospital with cuts to their faces.

And on New Year’s Eve Tuesday, just before 8 p.m., there was another attack near the Grand Avenue stop. A 22-year-old man was punched in the face and robbed.

Chicago Police said crime on the CTA has gone up two percent since Thanksgiving, but arrests are up too – to the tune of 180 percent.

Police said that is thanks to mobile teams and HD cameras.

Police further said they have increased police presence across the CTA. We checked the stops of the three aforementioned attacks and did find officers at all of the above locations.

Meanwhile Wednesday night, police told us about two more attacks on the Red Line this week.

There was another earlier attack on Sunday around 3:40 a.m. near the Harrison station. An assailant attacked 37-year-old man and robbed him, police said.

There was also an attack at 5:40 p.m. Tuesday near the Chicago Avenue stop. In that instance, another 61-year-old man was punched in the face and robbed by a male juvenile, police said.

One boy was charged in both of those cases. He was charged with two counts of robbery, and one count each of aggravated battery to someone over 60, aggravated battery causing great bodily harm, and aggravated battery to a peace officer.

Tara Molina