Credit: RJ Sangosti / The Denver Post/ Getty Images

Texas snowmobiler Caleb Moore remains in critical condition days after his snowmobile flipped on top of him in a violent crash during competition at the Winter X Games in Aspen, Colo.

The Moore family today released a statement to ABC News through family spokeswoman Chelsea Lawson saying, "Caleb is in critical condition and is being closely monitored."

"The Moores want to express their gratitude to all of Caleb's fans, friends and family for their strong support and ask for continued prayers in the coming days," the statement continued.

The 25-year-old medal-winning athlete from Krum, Texas, developed complications in his heart and brain after suffering an accident Thursday night during the Snowmobile Freestyle finals. Moore was completing a backflip when he came up short and the skis on his sled slammed into the landing, causing the 450-pound machine to flip end-over-end.

Moore went over the handlebars of the snowmobile and it came crashing down on top of him. He tumbled down the slope for several feet before coming to a stop at the bottom, where he lay on the ground for a few minutes.

Moore eventually got up and walked off the course with help, but he was rushed to Aspen Valley Hospital with a concussion, according to an X Games Medical report. While there, doctors discovered bleeding around Moore's heart and he was flown to St. Mary's Hospital in Grand Junction, Colo.

St. Mary's Hospital did not immediately respond to ABC News' request for comment.

Moore underwent emergency heart surgery Friday and has since remained in intensive care. But on Sunday, the Moore family released a statement through ABC's sister network ESPN saying, "his cardiac injury has led to a secondary complication involving his brain."

Moore's younger brother Colten Moore, 23, also competed in the Snowmobile Freestyle finals and crashed during the X Games competition. He was taken to the hospital with a separated pelvis but was released on Friday and "will not require surgery," according to Lawson.

Both Moore brothers are decorated Winter X Games veterans, who made their debut in competitive snowmobiling in 2010 in Aspen after years of racing ATVs.

Caleb, who has three Winter X Games medals, took home the bronze medal in Snowmobile Freestyle at last year's games, and stood next to his brother Colten on the podium, who had snagged gold.

UPDATE: An online fundraiser has been set up on behalf of the Moore family. For more information, visit the website.