Emergency warning siren malfunctions near San Francisco City Hall

An emergency warning siren near San Francisco's City Hall malfunctioned during today's regular noon test, triggering a number of nervous phone calls to emergency officials.

Instead of the short blast of sound usually produced by the city's warning sirens every Tuesday at noon, the siren kept sounding for around five minutes, which is what it might do in the case of an actual emergency, according to Francis Zamora, spokesman for the city's Department of Emergency Management.

"So obviously there was reason for concern and we got a lot of calls," Zamora said.

Zamora said the malfunction is exactly the kind of problem the weekly tests are intended to detect. The city gets electronic feedback from the system during the tests and also has listeners stationed around the city to detect any problems, he said.

The malfunction also coincided with an unrelated test of the AlertSF emergency text message system for National Tsunami Week. Those messages were clearly identified as tests, Zamora said.

If there had been an actual emergency, the sirens will broadcast warning messages, but residents are also urged to tune into the local news or sign up for AlertSF texts to get more information. People can sign up by texting the word "AlertSF" to the number 888777.