A SWAT operation is underway in Matteson involving FBI, CPD and Matteson: Officials

An armed person who pulled out a gun triggered a SWAT response Friday morning involving the FBI, Chicago police and Matteson police.

According to the FBI, police were attempting to locate a person when he pulled out a weapon and refused to comply with commands.

The situation in Matteson is not yet resolved and emergency responders are still on site, the FBI said.

This is a developing story. Check back later for updates.