Democratic presidential candidate Beto O’Rourke expressed regret Friday over writings he contributed as a teenage member of the Cult of the Dead Cow hacker group.

“I’m mortified to read it now, incredibly embarrassed, but I have to take ownership of my words,” Mr. Rourke said during a podcast taping in Cedar Rapids, Iowa, attendees reported. “Whatever my intention was as a teenager doesn’t matter, I have to look long and hard at my actions, at the language I have used, and I have to constantly try to do better.”

Reuters reported Friday morning that Mr. O’Rourke, 46, was secretly a member of the Cult of the Dead Cow in the late 1980s, making the presidential hopeful a participant in the nation’s oldest and continuous group of computer hackers.

Under the handle “Psychedelic Warlord,” Mr. O’Rourke contributed to electronic magazines, or e-zines, published online decades earlier by the hacker group, Reuters revealed. His submissions subsequently resurfaced later Friday, including a story he wrote when he was 15 that involved driving a car into a couple of children.

“As I neared the young ones, I put all my weight on my right foot, keeping the accelerator pedal on the floor until I heard the crashing of the two children on the hood, and then the sharp cry of pain from one of the two,” reads an excerpt. “I was so fascinated for a moment, that when after I had stopped my vehicle, I just sat in a daze, sweet visions filling my head.”

Mr. O’Rourke described the writings Friday as “really hateful, really bad stuff,” The Texas Tribune reported.

“It’s not anything I’m proud of today, and I mean, that’s that’s the long and short of it,” Mr. O’Rourke said of his involvement in the group during an earlier campaign stop Friday, The Des Moines Register reported. “All I can do is my best, which is what I’m trying to do. I can’t control anything I’ve done in the past. I can only control what I do going forward and what I plan to do is give this my best.”

Formed in 1984, the Cult of the Dead Cow made waves in the late 1990s when its member released a hacking tool, Back Orifice, that enabled users to remotely access computers running vulnerable versions of the Microsoft Windows operating system.

“There is no indication that O’Rourke ever engaged in the edgiest sorts of hacking activity, such as breaking into computers or writing code that enabled others to do so,” Reuters reported.

A former member of Congress representing El Paso, Texas, Mr. O’Rourke formally declared his presidential candidacy earlier this week. He unsuccessfully campaigned last year in the race won by incumbent Sen. Ted Cruz, Texas Republican.