DETROIT (WWJ) – Authorities say a gunman was taken into custody after showing up at the Fiat-Chrysler Jefferson North Assembly Plant in Detroit just hours after another man threatened to shoot up the facility.

The incident unfolded just before 9:30 a.m. Saturday, prompting a brief lockdown at plant — located on Conner Street between East Jefferson and Mack avenues on Detroit’s east side.

Police say a man — a former employee whose girlfriend works at the plant — showed up on the property with a gun, possibly looking to harm the woman. Jody Tinson, a spokesperson for Fiat-Chrysler, said the man entered the property through an area that is controlled by a contracted company where there is no type of security screening.

“An unidentified man was able to get onto our premises and into our plant with a gun,” Tinson told WWJ’s Rob Mason. “He was quickly apprehended by plant employees and the gun was removed from him.”

The workers held the man while police responded to the scene. He was then taken into police custody without further incident. No shots were fired and no one was injured.

Detroit Police Chief James Craig is now calling the eight union stewards who apprehended the gunman “heroes” for preventing a possible mass shooting from happening. Craig said the workers heard that a former employee had entered the plant with a .45 semi-automatic weapon and quickly sprung into action.

“What a great story. We’re talking about people working together to prevent what could have been a very violent outcome,” Craig told WWJ’s Laura Bonnell. “The individual, we do know, is wanted on a parole warrant. He was a former employee here as of probably eight months ago. His domestic partner is an employee here, and they’ve had some recent issues.”

Craig said the suspect is also a person of interest in at least four carjackings that took place across the city earlier in the morning. Charges including assault with intent — less than murder, and felony firearm are now pending.

“Starting at 6 o’clock this morning in different parts of the city, in fact we now believe that the final carjacking incident may have occurred on the grounds of the client [the assembly plant],” said Craig. “So again, we’re talking about a very dangerous suspect.”

First-shift employees were sent home after the “all-clear” was given. Second-shift employees are still required to report to work at 6 p.m., according to plant officials.

The incident happened about three hours after another man threatened to shoot up the assembly plant.

Authorities say a 29-year-old man distraught about a child abuse warrant arrived at the facility around 6:40 a.m. and was making threats toward a cousin who works there, saying he was going to shoot up the place and kill himself. Police responded and took the man into custody without incident. No one was injured and no weapon was recovered.

Investigators say the incidents are not connected. Tinson declined to comment on the earlier situation, saying she was not aware it took place.

Tinson said the company relies on their employees to know Fiat-Chrysler’s code of conduct and to be respectful of their fellow workers. With nearly 2,5000 people coming in for each shift, Tinson said screening employees and visitors or searching their bags are tasks that are nearly impossible.

Fiat-Chrysler is cooperating with police in the investigation, which is ongoing.

Stay tuned to WWJ Newsradio 950 and CBSDetroit.com for the latest.