Ronin Diedenhofen was walking through the lower-level of Woodfield Mall Friday afternoon when he saw an unusual sight: An SUV driving through the concourse.

At first, he thought it was being put out on display. Within seconds, he realized it was something different.

“It took me a minute to register what was going on,” said Diedenhofen, 19. “I heard a loud bang; it was the car hitting one of those little trains that kids usually ride in at malls. That was like, ‘OK, that’s not normal.’”

As it turned out, the driver had rammed through a side entrance to a Sears store just a few minutes earlier, around 2:20 p.m., on the east side of the mall near a Rainforest Cafe. From there, the 22-year-old man behind the wheel smashed into one store after another before crashing to a halt, according to Schaumburg police. He was held by shoppers — including two off-duty cops — and arrested minutes later by responding officers, police said.

Schaumburg Police Chief Bill Wolf said three people were taken to hospitals to be treated for “very minor” injuries; none were hit by the SUV. Another four were treated at the scene.

Dozens of police vehicles descended on the mall; officers ordered everyone out and blocked parking lot entrances. The mall remained closed through Friday evening, but Wolf said it was expected to reopen Saturday morning.

There was no indication the incident was an attack, Wolf said, or that the driver was a former employee or had any personal connection to the mall. One possibility being investigated, he said, is that the driver — who briefly walked into the mall just before going back outside and driving in — had some type of medical episode. Wolf said it wasn’t clear if or when charges would be filed.

Nathaniel Findlay, 21, was walking into the mall for the start of his work shift when he saw the SUV pull up to the Sears.

“He was approaching the door, and he came to a complete stop,” Findlay said. “I got a quick glance at him and you could tell real quick the gears were turning, he was thinking about it.

“And then he just accelerated right through the doors,” Findlay said. “He was not going to stop until he got inside that mall.”

Findlay went right back to his car and called his cousin who was inside the mall.

“Dude wherever you are, get down, get out,” he told his cousin. “There’s a car inside.”

Back inside the mall, Diedenhofen managed to pull out his cellphone and record much of the incident, later posting it to Twitter, where it quickly went viral.

“It was a safe distance away,” Diedenhofen said. “There was no way it would turn around and go for me, so I pulled out my phone and started recording.

“But you can even see on the video, I’m jumping back when he looks like he’s reversing, I’m not taking a chance,” he said. “It seemed like he was just trying to go for as much damage as he could.”

The video, posted about 20 minutes after the SUV first crashed through the doors of the Sears, shows the SUV driving around the mall and screeching its tires while terrified shoppers and employees run away.

People can be heard screaming as the car maneuvers between kiosks, crashes into one display of cellphone cases and makes its way through the first level of the mall.

“Yo, this is not happening right now,” a man can be heard yelling as the car drives past stores, including a Forever 21 and an H&M. “What the f---.”

One of the men seen running in Diedenhofen’s video is Abram Taylor, a district manager with Sprint who was visiting the phone company’s kiosk at the mall for the launch of a new iPhone.

“I heard a big loud boom, and I looked up and an SUV was coming straight toward the kiosk,” Taylor said. “When he started coming towards us, I’m trying to figure out which way he’s gonna come ’cus I’m trying to get the heck out of there. I wanna go the other way.”

Taylor, 39, said he made his move when the SUV crashed into a store and reversed before heading for the kiosk.

”He pulled straight forward and hit right into the kiosk. Missed me by maybe 10, 15 seconds,” Taylor said. “There was a lot of chaos, screaming, crying. It was dramatic. You didn’t know what was going to happen.”

Lateef Farooqui had just finished lunch in the food court when he heard the commotion. Many in the mall initially thought there was a person with a weapon.

“I hear people yelling and screaming, ‘Gun, gun, gun,’” he said.

Wolf, the police chief, later confirmed no shots were fired and no weapons recovered.

Farooqui — originally from the Chicago area, now living in Guadalajara, Mexico — said panic soon set in in the food court.

“It clears out very heavily; people are leaving their phones and computers,” he said, describing the driver’s route as a “pinball machine of hitting things.”

Lauren Carney said she had just parked and was happy she’d snagged a spot close to the mall door.

“Next thing I know, I heard kind of like a bang” as the car crashed through, she said.

Carney doubted the driver was going very fast when he entered the mall.

“He could not have been flying because I didn’t see him go by, I just heard it,” she said.

Moments later, a deluge of people ran out the entrance the driver had just passed through, and she was unable to move her car.

Upon being taken into custody, the driver’s demeanor was “pretty cool and collected,” Farooqui said.

Diedenhofen said he saw the officers arrest the driver after the commotion was over: “I looked straight into his eyes, and it was just a 1000-yard stare.”

As the suspect was being led out by police, Carney said, “he was very stoic. He just walked out. He was not wobbling and he didn’t appear to be under the influence.

“Knowing that he made it that far into the mall, there’s no way in your head you’d think that everybody was OK.”