A former security guard at the Caesars Casino in Atlantic City was sentenced to 11 years in state prison Friday for committing an armed robbery at the casino in 2014 after he was fired from his job, authorities said.

Izyiah Plummer, 22, of Atlantic City, pleaded guilty in August to charges of armed robbery, conspiracy, aggravated assault and weapons offenses, the New Jersey Attorney General's Office said.

Three other defendants have pleaded guilty and face prison sentences when they are sentenced March 17: Aaron Evans, 26, of Atlantic City; Nathaniel Greenlee, 23, of Bear, Del., and Donavon Jackson, 22, of Wilmington, Del.

The investigation revealed that Plummer, Evans, and Jackson arrived at the casino about 6:18 a.m. July 21, 2014, in a car driven by Greenlee.

Plummer and Evans went into the casino wearing masks and gloves, and confronted a security guard and another employee who were loading cash boxes onto a trolley at a kiosk. Plummer pointed a handgun at the employees, including at the security guard's head, while Evans removed three cash boxes from the trolley, authorities said.

As the two men fled, one dropped a cash box. But they got away, back into the getaway car, with two boxes containing about $181,200.

The four men then divvied up the loot. Authorities later found a black ski mask, bullets for a .38 special handgun and $43,900 in cash at Plummer's apartment.

Attorney General Christopher Porrino said in a statement: "Plummer planned and executed a violent armed robbery that put lives at risk."