Police search for caller who threatened Denver’s city hall

Police are trying to track down a caller who made an unspecified threat against Denver’s city hall that led authorities to temporarily lock the building down.

Deputy Mayor Murphy Robinson says Denver’s 911 service alerted security officials of the threat against the City & County Building at about 7:30 a.m. Wednesday.

He says not many people were inside at that hour. No one else was allowed in, and those inside were told to remain in their offices as officers searched the building twice.

Police haven’t released details about the nature of the threat. Public safety director Troy Riggs says more information will be released once the caller is found.

Mayor Michael Hancock says there have been “stepped-up aggressions” against public officials nationwide and the city won’t let the threat go.