SAN FRANCISCO (CBS SF) – Tweets and emails sent out by UCSF Wednesday afternoon set off fears of an active shooter situation on at San Francisco General Hospital.

UCSF is affiliated with San Francisco General, and was handling public relations on this incident. The KPIX 5 newsroom received the following email shortly before 1:24 p.m.:

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This is an important message from the UCSF WarnMe emergency notification system.
EMERGENCY: There is a police emergency at San Francisco General Hospital Bldg. 1, 3rd and 4th floors. There have been reports of shots fired at that location. SFPD and SF Sheriffs Tactical Units are conducting a room to room search of the location. If you are there, lock all access doors and stay out of sight or escape if it is safe to do so. All others avoid the area. Further information will be sent as soon as possible.

Which was followed up by this Tweet:

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News of the lockdown situation spread quickly online, and both KCBS and KPIX 5 dispatched crews  to the scene. Later UCSF said the building in question was clear, but a search for a suspect was ongoing.

However, just minutes later, KCBS was able to contact a media representative for the hospital.

“It’s a false alarm in the Internet age.  Within the hour, there was a loud noise reported at one of our buildings on campus and it was investigated.  Apparently, rumors began spreading and they spread to the Internet and got a little bit out of control,” said San Francisco General Hospital spokesperson Rachael Kagan.  “There was nothing to be found. We have the all clear here. There is not a problem. Everyone is safe.”

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An investigation has failed to turn up any evidence of a shooting, and it is not clear what created the initial sound mistaken for gunfire.