CHICAGO — A medical helicopter’s three-person crew is in good condition and a patient remains in critical condition after they crash landed on the South Side Saturday night.

The helicopter was transporting an unnamed patient to Christ Hospital when the pilot radioed there was an emergency around 9:15 p.m. Saturday. Shortly after the crew made its mayday call, the pilot made an emergency landing on a grassy area beside the Bishop Ford near 103rd Street.

All three crew members walked away from the crash, and are now listed in good condition. The patient they were transporting was in critical condition prior to the crash, and remains in the same condition.

Part of the Bishop Ford was closed after the crash, causing delays in the area. While the ramp to I-57 has since reopened, the ramp from the interstate remained closed as of 5 p.m. Sunday. Crews were still attempting to clean up the scene and tow the helicopter away Sunday morning.

Witnesses say they thought the helicopter might have had trouble because of fireworks, while investigators are still looking into the official cause. The Federal Aviation Administration and the National Transportation Safety Board have now taken over the investigation.

The FAA released the following statement:

At approx 9:15 pm, a Eurocopter 135 air ambulance helicopter crashed near 103rd street and the I-57 expressway in Chicago due to unknown circumstances. Local law enforcement reported that there were four to five people on board. Contact law enforcement or local hospitals for their conditions and their identities. The FAA will be on the scene to begin an investigation.