OAK LAWN, Ill. — One person is in custody on Monday after a shooting that left an off-duty Oak Lawn police sergeant injured.

According to Oak Lawn police, the shooting unfolded in the 10800 block of South Central Avenue around 12 p.m. Officers were called to the scene following reports that a person had been shot at a business in the area.

Police say a preliminary investigation has revealed that an employee arrived at the business and was involved in a verbal dispute with other employees before the shots were fired.

An off-duty Oak Lawn police sergeant who was working at the facility as a security guard, and another guard, were nearby and overheard the argument.

Police say at one point during the dispute, the employee turned around and walked away from the employees before he allegedly removed a semi-automatic handgun from his coat pocket.

According to officers, the employee then allegedly chambered a round and turned to engage with the off-duty police sergeant, the second armed security guard then fired a shot at the employee who had allegedly begun attacking the sergeant.

Authorities say during the alleged attack, the employee’s gun jammed, which offered the sergeant time to defend himself.

With the help of others at the scene, the sergeant and the other security guard were able to subdue the employee and place him in custody.

Police said the employee was able to fire five rounds and struck the sergeant at least twice in his Kevlar vest and once through his leg.

Following the attack, the sergeant applied a tourniquet to his leg and was taken to the hospital for treatment.

The second security guard suffered minor injuries and refused treatment at the scene.

Authorities say an investigation into the shooting continues and no one involved has been identified.