Police went floor to floor at an office building at 350 Rhode Island Street, which includes Samsara and a Sutter Health clinic.
MORE: Restaurant manager describes San Francisco active shooter investigation
There were two calls. At 12:15 p.m., an employee called to report a man with a knife or a stick. At 12:45 p.m., another call was made about an active shooter inside the building.
That prompted the large police response.
Lucas Walker was outside the building when they arrived. "I was surprised and worried. I was outside when it happened so I tried to connect with my co-workers that everything was OK," he said.
Inside the building, police went door to door but found no threat.
The employees all evacuated down the street.
A Samsara employee told ABC7 News that the company had planned to commemorate their fourth company birthday on Monday.
SFPD is investigating how a call of a man with a stick became one of an active shooter. They say part of that will involve speaking with the people who made those original 911 calls.
There were no injuries or shots fired during the incident. There were also no arrests and no known suspect.
Rhode Island St. Incident— SFPDSgtMike (@SFPDSgtMike) May 20, 2019
On 5/20/2019 at approximately 12:45PM, #SFPD responded to a building on the 300 block of Rhode Island regarding a possible active shooter. SFPD officers are on scene. At this time no shots have been confirmed. pic.twitter.com/cqWcVVQ7vS
There are no known injuries. Officers are searching the building and out of an abundance of caution, occupants are being evacuated.— SFPDSgtMike (@SFPDSgtMike) May 20, 2019