This is a representational image showing a Chicago police officer (left) and an unidentified ATF agent checking vehicles in Chicago, Nov. 6, 2002. Reuters/Frank Polich

UPDATE: 9: 18 a.m. EDT — The ATF agent, who was admitted in the hospital in a critical condition, was shot in the face. According to the Chicago Tribune, officials said his injury was not considered life-threatening. The report said the agent, who has not been identified, was part of a strike force formed last June. The aim of the group was to cut the flow of illegal guns into Chicago and crack down on individuals repeatedly arrested on gun charges.

The task force comprised of 20 ATF agents, along with 20 officers from the Chicago Police Department and the Illinois state police, authorities said.

Original story:

An ATF agent was in critical condition after being shot Friday in Chicago during a joint assignment with the city’s police force. The shooting took place in the 4500 Block of South Hermitage in the city's Back of the Yards neighborhood.

In a tweet early Friday, Chicago police spokesman Anthony Guglielmi said the Bureau of Alcohol, Tobacco, Firearms and Explosives agent was working with Chicago officers when the incident took place. The nature of the assignment was unclear.

“Officer hit, we need an escort to the hospital now!” an officer was heard saying on a police scanner, moments after the shooting. “We need an ambulance as soon as possible. Find someone to meet us. He may be hit in the head.”

A second officer involved in the incident was also hospitalized but was not shot, police said. The identity of the injured agent has not been revealed.

Local media reports said a manhunt is underway for a suspect. No one has been taken into custody so far.