EAST CHICAGO, Ind. (CBS) — “Beyond the call of duty” – that’s how the chief of the East Chicago, Indiana Police described the actions of one of his officers who was with his own wife and kids, but ran toward a shooting inside a Walmart.

The hero police officer sat down with CBS 2’s Lauren Victory on Monday.

High school sweethearts Bill and Nikki Johnsen weathered two kids, multiple moves, and a few career changes over the years. They never expected a shopping trip to a Hobart, Indiana Walmart on Sunday would land on their list of memorable experiences together.

“It was just a lazy Sunday to be honest,” Bill Johnsen said. “We were going to go buy some fishing stuff for my boys.”

But Bill Johnsen is an East Chicago police detective, and when one man shot another in the Walmart on Sunday, he stepped into action.

It was only half an hour into Johnsen and his family’s errands.

“I hear a gunshot; stop for a second, see if I hear any other ones,” Johnsen said.

There was then a strange noise from a neighboring aisle.

“It took 20 seconds before you hear people start screaming, and then they start stampeding towards the exit,” Johnsen said.

Johnsen pushed his wife and sons out the door, then turned around to go back in.

He said his wife advised him: “‘Stay out here. Let’s just go.’ But that’s not going to happen. It’s not what you’re trained to do.”

Detective Johnsen works with the Gangs and Narcotics Unit at the East Chicago Police Department. But at 3:50 p.m. Sunday, he was off duty with no handcuffs and no backup.

“I go back in, see the victim shot in the stomach. He’s hunched over holding himself. I get on the phone with 911,” Johnsen said. “The victim turns around points and says there’s the suspect there. By the time I start going that way, he’s laying on the ground, giving up. It never happens.”

The detective’s gut kicked in again before the alleged gunman could change his mind.

“I took his gun, disassembled it, and shortly after, two Hobart officers came in,” Johnsen said.

By then, the situation was under control. Hobart investigators determined the shooting involved two customers who knew each other – a spat that turned violent.

But with the rise of mass shootings, Detective Johnsen had no way of knowing what he was leaving his family to run toward.

Johnsen: “You don’t want anybody else to get hurt.”

Victory: “It’s like an instinct to you.”

Johnsen: “Yeah, it has to be. Otherwise, why are you in the job?”

The Johnsens never did get their fishing supplies, but they are thankful knowing there is always tomorrow.

The East Chicago Police Chief said of Johnsen: “Had it not been for his swift selfless actions, the situation could’ve been worse. He was able to stop the threat and prevent any further harm or danger to the patrons and workers inside of that store.”

The suspect in the shooting was taken into custody and was being held pending charges Monday.

Hobart police said they were still questioning witnesses to the shooting on Monday, and expected to present the case to Lake County prosecutors on Tuesday, to consider charges against the suspect.

A woman who was with the suspect also was taken into custody, but was later released without charges.

The man who was shot was taken to the hospital, where his condition was stabilized.

The Sunday shooting was the second shooting at the same Walmart in less than a year.

On Sept. 30, 2018 a gunman shot two people in the parking lot of the same Walmart. A 9-year-old boy and his 25-year-old father were wounded in the shooting.

One of the victims ran inside the store, alarming customers, according to police. At the time, employees at the Walmart store had just finished active shooter training a few days before.

Alex Cordell Hughes, 26, was charged in the 2018 shooting. Police said Hughes and the man he allegedly shot were in rival Gary gangs.

Lauren Victory