Four people were seriously injured when a medical helicopter crashed Saturday night near a stretch of highway on the South Side.

About 9:15 p.m., the Eurocopter 135 crashed into some grass near the junction connecting Interstate 57 and the Bishop Ford Freeway, according to the Federal Aviation Administration and Illinois State Police.

The helicopter crashed onto its belly, and its rotors were still intact when emergency crews arrived, according to Chicago Fire Department Deputy District Chief Lynda Turner. The helicopter was smoking, but it didn’t catch fire.

“The pilot did an excellent job of landing a helicopter that was in an emergency situation,” Turner said in a press conference.

Police investigate a helicopter crash about 10 p.m. Saturday, July 7, 2018 in the area of I-57 and I-94. | Justin Jackson/ Sun-Times

Police investigate a helicopter crash about 10 p.m. Saturday, July 7, 2018 in the area of I-57 and I-94. | Justin Jackson/ Sun-Times

Three of the helicopter’s occupants had evacuated by the time emergency crews arrived, according to Turner. Fire crews then removed the patient who was originally being transported.

Two people were taken to Christ Medical Center in Oak Lawn, while two others were taken to University of Chicago Medical Center, according to Chicago Fire Media Affairs. They were all listed in serious to critical condition. The conditions of three of the people have since been stabilized.

The cause and circumstances of the crash weren’t immediately known, according to state police and the FAA, which was investigating the crash alongside the National Transportation Safety Board.

Northbound lanes on I-57 and southbound lanes on I-94 remained closed Sunday morning as police investigated, state police said.

Police investigate a helicopter crash about 10 p.m. Saturday, July 7, 2018 in the area of I-57 and I-94. | Justin Jackson/ Sun-Times

Police investigate a helicopter crash about 10 p.m. Saturday, July 7, 2018 in the area of I-57 and I-94. | Justin Jackson/ Sun-Times