CHICAGO (CBS) — A helicopter crash on the South Side sent four people to the hospital.

That crash closed several lanes on northbound I-57 and southbound I-94.

CBS 2’s Chelsea Irving reports from the scene.

Both expressways are open. Crews removed the helicopter from crash site and onto a flatbed semi-trailer. Crews had to saws to cut the helicopters blades off.

The incident happened around 9:15 Saturday night. The pilot called a mayday before being able to put the helicopter down avoiding both expressways, nearby homes and a CTA facility.

On board were the pilot, a paramedic, a flight nurse and the patient. All four were taken to nearby hospitals. The crew is expected to be OK. The patient is in critical condition. However she was in critical condition prior to the crash.

Chicago police along with fire departments and state police all responded, but it is now the National Transportation Safety Board that is handling the investigation.

Preliminary results are expected within one to two weeks.