LA Sheriff reminds how to survive shooting

Keep a low profile, use cover to stop bullets and get out through any means possible, including emergency exits, windows and back rooms.

And if you can't get away, look for an improvised weapon as a last resort.

Just hours after the death of at least three people in a mass shooting in the Californian city of San Bernardino, the Los Angeles County Sheriff's Department has used a video to remind Americans of how to survive an active shooter.

Produced in March and re-broadcast on Twitter on Thursday (AEDT), the video points out that since 2006, active shooter events in the US with four or more deaths have occurred every 2.9 months.

The 10-minute video encourages Americans to make themselves as difficult to see as possible, and to keep a cool head by visualising the nearest safety route.

Police cannot arrive on the scene within seconds, and the video recommends using doorways, emergency exits, windows, back room doors or any other safe route as a fast means of escape.

If a safe exit cannot be made, the video urges Americans to enter a secure room and barricade all entries and exits, stay away from windows and remain silent.

Most active shooting incidents are over within 10 to 15 minutes, according to the video, and if escape cannot be achieved during this time, bystanders should look for improvised weapons to blind, inhibit or neutralise the gunman.

This should only ever be considered a last resort.

Given the high stakes of the situation, civilians should also co-operate with police at all times.

On average, twenty mass shootings occur in the US each year.