5:01 PM PT -- Chicago Fire producer Dick Wolf released a statement on Brown's death. He says, "The Chicago Fire family is devastated to lose one of its own. Our thought and prayers are with DuShon's family and we will all miss her."

5:25 PM PT -- Law enforcement sources tell us Brown was at home Friday morning when her family called paramedics because she was feeling ill. We're told she was taken to the hospital, where she died around noon. Her death is now being investigated by the medical examiner.

"Chicago Fire" actress DuShon Monique Brown has died after suffering an apparent heart attack.

Production sources tell us Brown admitted herself to a Chicago hospital a few days ago after suffering chest pains, we're told she went through tests but was released a short time later.

Things apparently took a turn for the worse Friday ... our sources say Brown died at home after some type of cardiac episode.

DuShon -- a Chicago native -- has been on "Chicago Fire" since the show started in 2012. She played Connie, the assistant to Chief Boden. She was also on "Prison Break" from 2005 to 2007.

DuShon has a background in social work and a Masters in Counseling and once worked as a counselor at a local high school.

Brown also starred in a made for TV movie titled "Public Housing Unit" about Chicago cops ... the project is set to premiere later this year.

She leaves behind a daughter.