A man who tumbled from the upper deck of Oakland Coliseum just before Thursday's NFL game was in serious condition in hospital early today.

The Oakland Tribune said the unidentified man had jumped, but other reports differed.

The fall occurred just after the 5:30 p.m. PT kickoff of the game, which the Raiders lost 26-13 to the Denver Broncos.

Oakland police officer Kevin McDonald said the man fell from the third deck and onto the concrete of the lower concourse, The Associated Press reported.

First reports called the fall an accident, but it remains under investigation, the officer said. No further information about the circumstances or his condition were available.

A statement from the Raiders said the team had no information beyond what authorities had released, but that their thoughts and prayers were with the man and his family and friends.