CHICAGO (CBS) — Two men were critically wounded in a pair of shootings downtown early Friday.

Police said, around 12:40 a.m., a 34-year-old man was shot in the stomach near Wacker and Wabash. Preliminary reports indicated there was an armed robbery near that intersection.

The man who was shot took himself to Northwestern Memorial Hospital, where he was in critical condition.

A 911 caller reported seeing as many as four individuals attack the victim. He said at least one of them was armed with a gun.

Raphael Mathis said he heard the shots and saw the aftermath.

“I just heard some gunshots, and I looked up, and I seen guys running,” he said.

Some business owners on Wacker Drive have called for the city to gate off a stairwell to Lower Wacker Drive near Wabash. They said criminals use it to attack people, and then get away.

A few minutes after the shooting on Wacker Drive, a 20-year-old man was shot in the stomach on the 5th floor of a parking garage on the 200 block of East Illinois Street in the Streeterville neighborhood.

The victim was taken to Northwestern Memorial Hospital in critical condition.

A person of interest was taken into custody at a bus stop near Illinois and Columbus, less than a block away from the parking garage.

Police said the circumstances of the parking garage shooting are under investigation.

Rajeev Sharma saw the first officers arriving at the garage after the shooting.

“I saw them drawing guns,” she said. “They were looking for somebody. They were running up the garage from all the way down. They were trying to scan the place, I think.”

A woman at the garage said someone broke into her car early Friday, and a large amount of money was stolen, but it’s unclear if that was related to the shooting.

Area Central detectives were investigating both shootings.