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MIAMI (CBSMiami) – From 2000 to 2013, the FBI reported 160 active shooter incidents. Sixty percent of those shootings ended before officers arrived. So what should you do to survive an attack?

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The Inland Regional Center nurse who shot video of Wednesday’s San Bernardino attack thought the heavily armed police storming the building were part of a drill.

She told the LA Times that the facility practices active shooter situations “every month or so.”

The frequency of active shooter incidents in the US is rising, and police are adjusting their tactics.

“First responding patrol officers are expected to go in and find that threat and stop the killing,” said Ron Hosko, former assistant FBI director. “They are not waiting for a SWAT team that may be fifteen minutes or an hour behind.”

Less than two weeks ago, the New York City Police Department held a three-hour active shooter drill in the city’s subway system.

“These exercises are vitally necessary, particularly in light of all that’s going on in the world at this particular point in time,” said NYPD Commissioner Bill Bratton.

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In January, the Los Angeles County Sheriff’s Department posted a video online with guidelines on how to survive a shooting of this kind.

Similar videos have been posted by other police departments and universities throughout the country.

Ohio State University’s video had several key tips.

“Lock or barricade the doors. Always spread out. Don’t huddle together, that creates one easy target.”

According to the Department of Homeland Security, active shooter incidents typically last between 10 and 15 minutes.

Washington D.C. Police Chief Cathy Lanier spoke to Anderson Cooper during a 60 minutes interview in November.

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“I always say if you can get out, getting out is your first option, your best option. If you’re in a position to try and take the gunman down, to take the gunman out, it’s the best option for saving lives before police can get there. And that’s kind of counterintuitive, what cops always tell people, right? We always tell people don’t, you know, don’t take action – call 911. Don’t intervene in the robbery. We’ve never told people, take action. It’s a different, this is a different scenario,” she explained.