It was a hobby that didn't get old.

On weekends, Dave and Ethan Mortensen of Cedar Rapids would seek out a spot near railroad tracks where they could watch trains pass.

“Ethan would watch trains, and my dad would read books,” older brother Jacob Mortensen said. “He could watch trains for hours."

Ethan, 32, had a developmental disorder, but was becoming increasingly independent, Jacob said. He moved out of his father’s house and was learning to drive.

Authorities believe the father and son were watching trains and practicing driving April 14, when their SUV ended up on the tracks. It was struck by a train traveling around 60 mph.

The crash killed them both.

"It's a very tragic accident," Cedar Rapids police spokesman Greg Buelow said.

Buelow said an investigation determined Ethan's inexperience as a driver was likely a factor in the crash, but police may never know exactly what caused him to lose control of the vehicle.

The Chevrolet Equinox left the parking lot of the Tait Cummins Sports Complex and crossed a ditch before reaching the train tracks.

There are no fences or barriers between the adjacent parking lot and the tracks, Buelow said.

Jacob said the sports complex parking lot was a location his father and brother would often visit to watch the trains together.

The crash occurred just a day after another fatal car versus train crash near Burlington, where three women were killed while crossing a train crossing controlled only by a stop sign.

There have been at least seven railroad-related fatalities in Iowa so far this year. A 23-year-old pedestrian was killed by a train Jan. 23 while walking on tracks in Ottumwa. Last Friday, authorities reported a pedestrian was fatally struck by a train in Iowa City.

There were nine railroad-related fatalities in Iowa last year, according to the Federal Railroad Administration.

Funeral services for Dave and Ethan were held April 18 in Cedar Rapids.

Dave, 66, grew up in Minnesota. He married his childhood sweetheart, Nancy Burk, in 1977.

Jacob said his parents met as children while vacationing with their families at the same northern Minnesota resort. They looked forward to seeing each other every summer and eventually started dating, he said.

They were married 36 years when Nancy died in 2014. She was 60.

Ethan graduated from Mount Vernon High School in 2005. Jacob said his brother was diagnosed with a pervasive developmental disorder as a child.

“It’s always been challenging,” he said. “But we encouraged him to try things. As he got older, he reached for those things more.”

Ethan eventually moved out of his father’s Cedar Rapids house and into his own downtown apartment. He worked and volunteered for a variety of organizations, including the Cedar Rapids Public Library, the Cedar Rapids Police Volunteer Corps and the Catherine McAuley Center, a nonprofit that serves immigrants, refugees and women experiencing crisis.

He was part of a Special Olympics bocce team. His dad would sometimes fill in as a volunteer coach.

“The week before he passed away, Dave was telling me how Ethan was taking driver’s ed and being very successful at it,” coach Kelly Gesling said. “He was very independent. Very successful at it.”

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Gesling said Ethan's teammates plan to wear commemorative buttons when they play in the Iowa Summer Games next month in Ames.

Both Ethan and Dave were active in the Cedar Rapids community, often together. One of their hobbies was speaking over ham radio. As members of the Cedar Valley Amateur Radio Club, they assisted with storm spotting and monitoring race courses for local marathons.

Club president Scott Haney said they “knew everybody” in the ham radio community and attended nearly every club event.

“I was a little startled on that Sunday evening when I did not hear them check in,” he said. “Then I found out why. That hurt, kind of like getting kicked in the chest.”

The father and son also served as ushers and greeters at First Presbyterian Church in Ely, where Dave was also a ruling elder and chairman of the church’s personnel committee.

The Rev. Julie Schuett said Dave was a wise leader with a keen wit and genuine humility. “Ethan was kind-hearted and loved by all,” she said.

Jacob said he believes that's how his dad and brother will be remembered.

“I’ve heard from so many people that they were having a bad day and then they would talk to Ethan and he would brighten up their day with his smile and demeanor,” he said. “They’d say he’s just the smiliest, kindest person they'd ever met."