UPDATE: U.S. Capitol building no longer on lockdown.

The Senate sergeant at arms issued a lockdown alert for the building and visitor center, saying police activity has been reported. Capitol office buildings are open.

Capitol police say they are searching for an individual but offered no details. One officer outside the Capitol said police are responding to sketchy reports of woman who may have a gun.

House press gallery staff says the building is on lockdown but that the House met briefly and immediately recessed. Voting scheduled to begin at 9:15 a.m. is postponed, gallery staff said.