Scores of police cars and ambulances rushed to Roundhay Road at 8.46pm last night after reports of a serious collision.
The driver of one of the cars involved was found unconscious at the scene of the crash and was immediately taken to Leeds General Infirmary.
West Yorkshire Police confirmed to the Yorkshire Evening Post today that the man, a 48-year-old, was thought to have serious brain injuries, but no further update on his condition has yet been made available.
The 26-year-old driver of the other vehicle involved in the crash was interviewed by police at a station last night.
A cordon was put in place on the road last night but the road has since been reopened.
A passer by who saw the crash scene said: "I saw at least six vans and lots of cars. I only drove past as I had to go up Roseville Road as it was cordoned off I didn't wait around to see.
"I presumed it was a shooting as I've never seen that many police cars together in my life and I have lived Chapeltown in over 34 years."