This photo of John DeReggi and his girlfriend Natalie Crim was taken by Crim’s sister moments before DeReggi was struck and killed by a train on Monday in Boyds, Md. (Courtesy of Crim Family/Courtesy of Crim Family)

John DeReggi, 16, and his girlfriend wanted to get their pictures taken at a picturesque spot near their homes in Boyds, Md. It was near railroad tracks. Lots of kids have been getting their photos made there.

“I love you,” he told his mom, Christine, as he left his home Monday afternoon, the words he always said as he left.

Just 20 minutes later, Christine DeReggi’s phone beeped. It was her son’s girlfriend.

“John got hit by the train!” she screamed.

Christine DeReggi drove less than a half-mile, got out of her car, and saw several people tending to someone.

According to Montgomery County police, a northbound Amtrak train struck John DeReggi, 16, just before 5 p.m. on Sept. 14 in Boyds, Md. (WUSA9)

“I ran down the tracks and found him,” she said.

According to Montgomery County police, a northbound Amtrak train struck John DeReggi just before 5 p.m. Monday in the community of Boyds, about 25 miles northwest of the District.

Investigators were still trying to learn precisely what DeReggi did in the moments before he was struck. According to his friends and family members, he went there with his girlfriend, Natalie Crim, and Natalie’s twin sister, who planned to use at least one of the photos as part of a school assignment.

When the train came, according to the friends and family, the girls went in one direction and DeReggi tried to go in the other, but he didn’t get out of the way in time.

One thing seems clear: The train, estimated to be traveling at more than 70 miles an hour, was moving much faster than he realized.

Several factors could have been in play. Trains are quieter than people think; their size makes them look slower; if they’re coming right at you, gauging speed is difficult.

“There’s very little clicketyclack. They can really sneak up on you,” said Robert Halstead, president of IronWood Technologies, a firm that reconstructs train accidents.

He likened the deceptive speed of trains to those of planes as they’re landing. Even though planes are going 150 mph, “it kind of looks like they’re just hanging there.”

The death of DeReggi — widely described as gregarious and adventurous — stunned not just students at Clarksburg High School, where DeReggi had just started his junior year, but schools nearby as well. His two sisters, mother and father — and those closest to him — are devastated.

“Every time I looked at him, he took my breath away,” Crim said. “Everybody loved him.”

Capt. Darren Francke, commander of the Montgomery Police Department’s major crimes unit, said detectives do not believe that anyone pushed DeReggi or that he wanted to be hit. Beyond that, Francke declined to say what happened just before the train struck, saying detectives are going through witness statements. He said that at this point in the investigation, it does not appear that the train operator did anything wrong.

Francke said many people underestimate the sound and speed of trains.

“A train in real life is different than what is often portrayed on TV and in the movies,” he said.

John Martin DeReggi Jr. was born on Nov. 2, 1998. His mother began calling him John-John to distinguish him from his father. As he grew up, they became close, ending phone conversations by saying, “I love you.” It became such a habit for DeReggi that he accidently started to end his conversations with friends that way, generating laughs, and he decided to do it with everyone, according to his mother.

By age 11, he’d started talking about wanting to become a police officer.

The family lived near a lake in Boyds, and DeReggi collected turtles, eventually housing about 30 inside terrariums at his home.

He began mowing large lawns near his home, calling his business “J&J Landscaping,” and doing well enough to purchase two large mowers — one of which cost $3,500, his mother said.

And he developed an adventurous streak, swinging from a rope into the water. He liked riding an elongated skateboard on streets. “He lived life to the fullest. That’s how he was always,” said Baleigh Louro, 16, a close friend.

He picked up the term “savage,” used these days to describe something that is bold and impressive. “His slogan was ‘Live Savage, Never Average,’ ” said Crim, his girlfriend. “Wherever John was he was having a good time and lighting up people’s day.”

This year, his mother said, he buckled down on honors classes. “His future was becoming more important to him,” his mother said.

Montgomery County students had no classes Monday because of the Rosh Hashanah holiday. DeReggi initially planned to mow one of his clients’ yards. His mother drove him to the house, but the mower quickly broke, unable to go forward.

DeReggi returned home.

Louro, one of his friends, said she spoke with him at some point Monday afternoon. He seemed to be in good spirits and spoke of his upcoming one-year anniversary with his girlfriend.

DeReggi and his girlfriend made plans to have her sister photograph them.

He took a shower, put on a nice shirt. His mother joked that he smelled nice. They said, “I love you” to each other. And he went out the door on a beautiful September day to the spot that seemed great for photos.

At some point, the three moved close to the tracks. Police think DeReggi made his way onto the tracks. The train came fast.

“As soon as it was upon them, the two girls ran one way and John ran the other, and John was hit,” his mother said.

Stephen Whiting, principal of Clarksburg High School, said his school of nearly 2,000 students was in mourning Tuesday, with psychologists and counselors on hand for students who needed support. Just last week, he said, DeReggi had helped the school’s 11th-graders win a mummy-wrapping contest at a pep rally.

He was a big personality and well-liked, with a large group of friends, Whiting said.

“He was a fun-loving kid, kind of the life of the party, always a smile on his face,” the principal said. “Very energetic. Everything he did, he did with enthusiasm.” The teenager participated on the track team, he said.

On Tuesday, many students wore blue, their school color, in his memory, Whiting said, and the school day ended with a moment of silence. On Tuesday night, friends and family gathered for a vigil.

“We’re all walking through a nightmare right now,” DeReggi’s mother said earlier in the day. “Everywhere we turn, it’s bad.”

Dana Hedgpeth, Jennifer Jenkins and Fenit Nirappil contributed to this report.