OKLAHOMA CITY - Wednesday’s shooting in San Bernardino is the 355th mass shooting in 2015.

Experts say three key actions to know in an active shooter situation: run if you can, hide if you can't escape and at last resort, fight your attacker.

Across the nation, businesses and schools are now bringing in experts to teach workers how to respond to active shooter situations.

Randall Yount is a former law enforcement officer. He now teaches a course he wrote at Oklahoma City Community College.

Yount explains it takes our brains up to a minute to react to hearing a gunshot.

“People automatically might tilt their head and ear that direction and just go on about their business and it really not get their attention,” Yount said.

It's during those seconds we need to be looking for our route to safety, whether it be running or hiding. And when confronted by your attacker, Yount said to fight.

“The biggest thing that you do in stopping something like this is if you attack is you interrupt them , you surprise them,” Yount said.

Yount said you must always be aware of your surroundings and know how to escape in an emergency.

He said it's now our responsibility to be prepared and take the extra steps in protecting ourselves where we work or go to school.

“We have to respond to it differently than we ever responded before. And the only way to do that is to go into a situation where you can be trained and know what to do when this happens,” he said.

His next training course will happen in January at OCCC.