PORTAGE, Ind. — A 3-year-old boy was killed and his 2-year-old sister seriously injured after they were struck by a freight train Tuesday morning.

Bryon Benson says his 3-year-old grandson Caleb Wilson and 2-year-old granddaughter Ellie Wilson must have crawled out of a hole in the screen door of their home in the Woodland Village Mobile Home Park sometime Tuesday morning.

“It’s dumbfounding to me how they even got out. With three grown adults, not on drugs not drinking state of mind,” Benson told WGN. Kelsey’s a good mom. She has been from day one.”

Even though there was a children’s gate loosely covering the hole, they got out and made their way to the CSX railroad train tracks four houses down.

“By the time the mom went to check the laundry, she came back and said, ‘dad, the kids are gone.’ I got on my shoes. I went one way, my brother went the other way, she went another way,” Benson said.

But no one thought to check the train tracks first, because Benson says the toddlers never played there. Then around 9:30 a.m., residents in the mobile home park heard the horns blowing and a train screeching to a halt.

“At three and two, kids don’t know how powerful a train can be. Even if you’re walking by you can get sucked under,” Benson said.

The conductor of an eastbound CSX train later told police he saw the children on the tracks and blew the horn while attempting to stop the train, but he was unable to avoid striking them. The first officer on the scene said Caleb was dead on impact. His sister Ellie has head trauma but she was actively crying. She was airlifted to Comer Children’s Hospital at the University of Chicago.

“These kids were loving kids. Caleb, he was a terror but a joy to be around. Fun to be around, always wanted to be by his mom, always,” Benson said. “Ellie always followed her brother.”

An autopsy will be performed on Caleb Wednesday, according to the Porter County Coroner. Portage Police Department Chief Troy Williams said once their investigation is complete, he will send the outcome to the state’s attorney’s office.

The Wilson family is now at Comer Children’s Hospital, waiting at the bedside of 2-year-old Ellie, and praying she pulls through.