A mentally ill man jumped to his death from an upper level of the new Seahawks Stadium during an open house for fans yesterday, according to the Seattle Police Department.

Witnesses saw the man, thought to be in his mid-30s, climb a 3-foot railing and jump from a ramp on the northwest side of the stadium shortly before 1 p.m. He fell about 40 feet and landed on a concrete plaza.

Emergency crews responded immediately and began resuscitation efforts but the man died at Harborview Medical Center less than an hour later.

"He did not fall, he jumped," said Seattle police spokeswoman Deanna Nolette. "All indications are it was an intentional act done by a man with a history of mental problems."

The man's identity was not released but his family told stadium staff that he had suffered from mental illness, Nolette said.

She said the incident was a suicide and any further investigation will be handled by First & Goal, which represents the stadium.

The King County Medical Examiner's Office has scheduled an autopsy for tomorrow morning.

"Our hopes and thoughts are with the victim and the victim's family," said First & Goal spokesman Jeff Klein.

"We are working closely with the authorities on the investigation and take this accident very seriously."

The upper levels of the stadium are outfitted with 3-foot-high metal rails. Witnesses said the man fell from the second or third level.

Fans had been invited to tour the $430 million, 67,000-seat stadium built on the site of the old Kingdome.

The stadium hosts its first NFL exhibition game Aug. 10, when the Seahawks play the Indianapolis Colts.