(CNN) -- A man died Tuesday at Niagara Falls from his injuries after going over a wall and falling into the gorge, authorities said.
Ontario's Special Investigations Unit (SIU) is investigating the death.
Shortly after 5 p.m. ET, an officer with the Niagara Regional Police Service was chasing a man, the agency said. Some time later, both fell into the gorge.
The officer, who police declined to identify, sustained a broken femur and was airlifted to Hamilton General Hospital.
The man who was with him died.
Video from the scene first showed the rescue of the officer. A firetruck ladder extended over a cliff.
Then what looked to be the second individual was raised from the gorge on a stretcher. The body was still, and wrapped in white sheets. It was loaded into a waiting ambulance.
The SIU has assigned seven investigators and two forensic investigations to the case. The agency conducts criminal investigations into circumstances involving police and civilians that have ended in serious injury, death or allegations of sexual assault.