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MEMPHIS, Tenn. — The O’Cielo Mexican Bar & Grill was quiet midday Friday, but neighbors say it is packed in the evenings. The owners tell us they have plenty of security.

After a shooting at the restaurant Wednesday night, one of the security guards at the restaurant is in jail.

O’Cielo managers say David Alexander was working security detail when two men, who weren’t allowed inside the restaurant, opened fire. Alexander allegedly returned shots, killing an innocent customer.

The restaurant managers say Alexander had only worked there a few months and was sent by a security company they hired.

One of the managers told WREG he had seen Alexander’s gun permit and assumed he had a security license too.

Turns out he doesn’t.

“A lot of people don’t. I don’t think they understand there is a lot you need to learn,” said Jeremy Brooks, a handgun trainer at Global Training Academy and Gun Range.

He says anyone who is working as a security guard in the state of Tennessee is supposed to be licensed.

“Knowing your laws, carrying your gun, when to pull your gun and not to. It’s very serious. You are putting your life at risk, not knowing what to do. You are putting other lives at risk not knowing what to do as well,” said Brooks.

The Academy offers weekly classes for state licenses. Classes are essential when it comes to teaching guards how to handle tense situations.

One  man who works as a licensed security guard in Mississippi says things should have been handled differently.

“If he didn’t have no license, he should have just called police and not shot back,” the guard told us.

Training can be the  difference between life and death.

“Usually in a stressful environment, our adrenaline kicks in. You start making decisions based off of emotion,” said Djenada Dunlap, a security trainer with Global Training Academy.

The District Attorney’s Office says in Tennessee acting as security guard without a license can carry up to a year in jail and $2,500 fine.

O’Cielo managers told WREG they have the name of the security company they used, different from the name previously released, but now they are going to let their lawyer release it along with security video they say shows what really happened.