The state courthouse in downtown Las Vegas was closed for about an hour Friday morning after a man told a 911 police dispatcher that a gunman in a wheelchair intended to kill a judge.

A floor-by-floor search by police and court guards after the 9:30 a.m. call turned up no gunman and no evidence that the threat was real, authorities said.

"There was no confirmation this was a valid call," Las Vegas police Lt. David Lewis said after more than 30 police officers joined dozens of armed court bailiffs and marshals in a search of the 17-story Regional Justice Center.

"We searched the entire facility," Lewis said. "It was negative for any guns or suspects."

Court sessions stopped, judges were taken to their chambers and public areas were cleared during the search, but most of the more than 3,000 people believed to be in the building were told to remain where they were in courtrooms or offices, said court marshal Lt. George Glasper.

Public entrances, which are equipped with metal detectors and staffed by security officers, reopened about 10:30 a.m.