Exodus Tyson's 7-year-old brother found her on a treadmill with her neck on a cable attached to the exercise machine, police Sgt. Andy Hill said, calling it a "tragic accident."

The mother sent the boy to find the 4-year-old girl who was playing in a separate room. The boy found his sister in distress and got his mother, police said.

"Somehow she was playing on this treadmill, and there's a cord that hangs under the console — it's kind of a loop," Hill said. "Either she slipped or put her head in the loop, but it acted like a noose, and she was obviously unable to get herself off of it."

The girl's mother took her daughter off the cable, called 911 and attempted to revive her.

Responding officers and firefighters performed CPR on the girl. She was rushed to nearby St. Joe's Hospital after she was found around 10:30 a.m local time, MyFOXPhoenix.com reported.

Hill said former heavyweight champion Tyson had been in Las Vegas but flew to Phoenix immediately after learning of the accident.

Tyson could not immediately be reached for comment. Calls to three of his representatives were either not returned or not answered.

Hill said everything in the investigation pointed to an accident. "There's nothing in the investigation that revealed anything suspicious," he said.