They say the alarm was set off by mistake.
According to police, officers arrived on scene just after 11:20 a.m. to the 300 block of Avenue H at the Harvey Milk Memorial Administration building.
"At this time we have not confirmed an active shooter incident or located any victims," a police spokesman told ABC7.
SFPD says someone in the building triggered the alarm to report an active shooter.
But after officers searched room by room, they determined there was no threat in the building or anywhere on Treasure Island.
Police were conducting an unrelated active shooter drill in the city's Sunset District, which caused confusion, officials said.
TREASURER ISLAND INCIDENT— SAN FRANCISCO FIRE DEPARTMENT MEDIA (@SFFDPIO) August 11, 2021
YOUR @SFPD ARE ON SCENE OF AN INCIDENT ON @SFTIDA WITH NO INJURIES AND NO SHOTS FIRED
YOUR @SFFDPIO AND @SFPD HAVE A NON-RELATED ACTIVE SHOOTER DRILL IN THE SUNSET WHICH CAUSED CONFUSION. THANK YOU TO OUR MEDIA PARTNERS FOR CONFIRMING THIS INFO pic.twitter.com/OfaFc45AZx