An Amtrak police officer shot a person about a block south of Union Station on Wednesday night in the West Loop, authorities said.

Emergency crews responded about 8:45 p.m. to the intersection of Van Buren and Canal streets, and a male was taken in critical condition to Stroger Hospital, according to the Chicago Fire Department.

A law enforcement source said an Amtrak police officer opened fire while responding to a robbery. The officer was not hurt.

Chicago Police referred questions to Amtrak police, who did not immediately respond to requests for comment. It was unclear what agency is investigating the shooting.

The shooting occurred in the middle of the block on the east side of Canal, which was blocked to foot and vehicle traffic between Jackson and Van Buren, where about 15 law enforcement officers congregated.

Police vehicles from the Amtrak, Metra and Chicago police departments remained at the scene as of 10 p.m.