BATON ROUGE - A gas station employee was saved from a knife-wielding assailant by a firefighter who happened to be in the store's parking lot when the attack unfolded, officials said Sunday.

The East Baton Rouge Sheriff's Office said the incident happened around 5:30 p.m. after the suspect, 23-year-old Vernell Parker, had spent hours hanging around the business on Greenwell Springs Road.

Witnesses said Parker was talking to himself as he tried to force his way behind the front counter and pulled out a large knife when a cashier went to stop him. Parker then allegedly knocked the employee to the ground and stabbed the victim multiple times.

The sheriff's office said a Baton Rouge firefighter, identified as Fire Inspector Aaron Johnson, was in the parking lot when another employee ran outside shouting for help. The firefighter armed himself with a handgun and ran inside to confront Parker while the other employee called 911. 

Johnson held Parker at gunpoint and ordered him to let the cashier go. Once the victim escaped, Parker allegedly went for the gun and got into a struggle with the first responder. 

Investigators said the gun went off during the ensuing fight, and Parker ended up on top of Johnson for "several minutes." Parker eventually got up and began pacing behind the cash registers until deputies arrived, according to arrest documents.

"Our guys run into burning buildings every single day across this city to risk their life. That's what we do. To engage in an encounter like that, we're not prepared for that, right? Our guy went above and beyond yesterday," Baton Rouge Fire Chief Michael Kimble said. 

Parker later told deputies he suffers from schizophrenia and had not taken his prescribed medication for months. He claimed voices in his head told him to carry out the attack and that he did not mean to harm anyone. 

Parker was booked into the East Baton Rouge jail for attempted second-degree murder. 

The Baton Rouge Fire Department said Johnson is currently on paid administrative leave. 

The sheriff's office said the victim is expected to be OK.