Updated 01/19/15 – 2:23 p.m.

CHICAGO (CBS) — A woman was killed and a man was critically injured, when their car crashed and rolled over onto the frozen surface of a lagoon in Lincoln Park.

Police were trying to figure out what caused the driver to lose control and drive onto the frozen surface of the lagoon in the 2200 block of North Lake Shore Drive around 1:45 a.m.

The car flipped upside down, landing on the frozen lagoon. The ice held, and the car did not end up in the water, but a man and woman were pinned inside.

Firefighters held onto a rope as they crawled out on the ice, and made their way to the car to get to the driver and passenger, who were trapped inside.

Rescuers had to be careful not to fall through the ice, in case it had thawed to dangerously thin levels due to the warmer weather over the weekend.

Crews used the Jaws of Life to pry open the mangled metal, and pull the victims out.

The woman was taken to Northwestern Memorial Hospital, where she was pronounced dead at 2:30 a.m. The man, who was driving, was taken to Advocate Illinois Masonic Medical Center, where he was in critical condition Monday morning.

Police said the crash appeared to be alcohol-related. Charges were pending against the 42-year-old male driver.