A shooting inside a busy Loop CTA station left a 27-year-old man seriously wounded and brought the Thursday evening rush hour to a halt for thousands of downtown commuters.

The targeted attack happened about 5 p.m. in the pedestrian tunnel connecting the Red and Blue lines at Jackson, according to Chicago Police Chief of Patrol Fred Waller.

A gunman wearing a blue surgical mask and a blue hoodie walked up to the 27-year-old toward the east end of the tunnel and fired two shots at close range, hitting the victim once in the hip, Waller said.

The shooter took off to the west end of the tunnel, either hopping on a Blue Line train or leaving the station, Waller said. No one was in custody Thursday night.

The wounded man was taken to Northwestern Memorial Hospital in serious condition, authorities said. No one else in the crowded tunnel was injured.

The victim was “very uncooperative” with detectives and likely knows the shooter, Waller said. He was alert and talking in the immediate aftermath of the shooting, but he put on earphones in the ambulance rather than speak to investigators, a police spokesman said.

“This area is probably one of the safest areas in the city,” Waller said outside the station. “This is a targeted incident, so riders should not feel any type of discomfort or any type of hesitation on riding the CTA.”

Blue and Red line trains were disrupted for about an hour after the shooting. Police also blocked off most traffic on the normally bustling State Street, where officers could be seen escorting at least one young man into the back of a squad vehicle.

“You really can’t get away from the shooting in Chicago,” commuter David Terrance said.

Waller said detectives were interviewing several cooperating witnesses and reviewing surveillance video from the numerous high-definition cameras that blanket the tunnel and station.

The Jackson station was the scene of another shooting in August 2017, when a man was shot on a Red Line train as it pulled into the stop. The alleged shooter in that case was arrested a few days later and remains jailed ahead of trial.