More than 1,500 people streamed out of Civic Center buildings as emergency vehicles descended on the plaza Friday morning.

A multi-agency work group aimed at disaster preparedness held its second joint evacuation exercise today, called “Civic Response 2011.” Alarms sounded at 10:30 this morning in several local and state buildings, including San Francisco’s Department of Public Health, the Public Utilities Commission and Hastings College of the Law.

Michael Trevino, spokesman for the exercise said this year, they tried to change it up a bit by keeping area roads open.

“In the event of an actual emergency you probably wouldn’t have the streets already closed for people to come across,” said Trevino. “We introduced that wrinkle today.”

City Hall employees didn’t seem to mind the unexpected break. But the drill did disrupt a few weddings.

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No sooner had Lindsay Crittenden said, “I do,” when the alarm sounded.

“And I started laughing,” said Crittenden, “because it started going ‘wooh wooh’”

Edith Jaime and her fiancé Jacinto weren’t quite as lucky. They had to settle for a ceremony on the sidewalk in front of City Hall. But Edith said the change of venue didn’t dampen the occasion.

“It was fine for me, it was more fun, said Edith. “I thought it was not so special, but once you’re in it, it was nice.”

In less than an hour, employees were back at work.

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