'16 and Pregnant' Star Sean Garinger Dead at 20 After ATV Accident

Sean Garinger of "16 and Pregnant" has died after a horrific freak accident involving an ATV -- and it sounds like the elements might be to blame for this.

The reality star -- who appeared on Season 6 of the hit MTV show, which aired during the pandemic -- passed away late last month at his home in North Carolina during a routine parking job ... this according to his mother, Mary, who spoke to The Sun.

The description of what happened here is absolutely tragic -- Mary explains that Sean was simply moving one of their ATVs from one parking spot on their property to another so that she could pull her own car in ... and while he was driving, the ground underneath gave in.

Mary says the foundation of the ground there had been eroded due to the mud and rain -- and when it caved in from under him, it caused the ATV he was on to flip ... with Mary saying he got pinned. She says it made contact with his head, and crushed his skull.

She goes on to say that she tried calling for help to get the ATV off of him, but by the time she came back to check on him ... she says she realized he wasn't responsive anymore.

Mary says that she laid next to her son until an ambulance arrived, adding ... "There was a huge part of my heart that died with my son on Wednesday. He was my only son, my rock, my strength when I had none left."

Sean shared two young children with his ex, Selena Gutierrez ... who appeared on the show with him. She doesn't appear to have addressed his passing just yet.

He was only 20.