The tree fell around 7:20 a.m. at Addison Street and Cumberland Avenue. The man was taken to Lutheran General Hospital in Park Ridge.
The victim is 33-year-old Jerzey Szezepanek of Des Plaines. Upon arrival at the hospital, police say, the victim had no vital signs. Doctors were able to revive him.
Szezepanek was headed southbound on Cumberland toward Addison in a flooring company van when a dead tree fell onto his vehicle. That stretch of Cumberland Avenue runs alongside the forest preserves.
The crumpled white van shows where the rotted tree fell on the roof over the driver's side where Szezepanek was sitting. He had been driving southbound on Cumberland approaching Addison when the accident happened.
Newcomers gathered at the scene Wednesday and talked with others who saw what happened.
"I spoke with one of the gentleman who actually did see it happen. He described it as happening in slow motion. The tree just fell right down in front of him," said David Ullrich.
Witnesses called for help. One woman tells ABC7 that people tried in vain to get the tree off of Szezepanke's van. She felt his pulse stop as both Chicago police and fire departments arrived.
The fire department says it took nearly an hour to extricate him and that they were trying to give him medical care while removing the tree. He was taken in critical condition to the hospital.
Back at the scene, the tree was chopped up and removed while people who heard about what happened talked about their own close calls.
"I was driving southbound on Cumberland Avenue, perfectly clear, sunny day, no wind. And a dead tree fell on my car, totaled out my mini-van. Six more inches, it would have been through the windshield," said Pat Pisano.
Szezepanek is a driver for a flooring company. His wife is reportedly with him at the hospital.
Cumberland was temporarily blocked in both directions between Addison and Irving Park Road during the morning commute.
