FOXBOROUGH, Mass. -- As stunned bystanders watched, a Patriots fan on his way into Gillette Stadium for Sunday's game leapt off an overpass and fell 17 feet onto the pavement below.

"He thought he was going to land in a snow bank," said one witness to the incident.

NewsCenter 5's Todd Kazakiewich reported that the 20-year old man was on a pedestrian walkway heading towards the stores at Patriot Place about 3:15 p.m.

"All of a sudden he jumped. He was screaming on the way down, then he was silent," said another witness.

The man bounced off the pavement below.

"He was unconscious and unresponsive," said Scott Rogers of Foxborough Fire and Rescue.

A medical helicopter landed on the Patriots' practice field and flew the man to Beth Israel Deaconess Medical Center in Boston. Officials there said he was in serious condition.

Police are investigating whether alchohol was involved.

"He definitely had something to drink. I think he had a great deal to drink," said a man who witnessed the incident.