A grandson of Vail's co-founder died Tuesday in an avalanche while he was skiing near the resort in an area notorious for deadly slides.

Tony Seibert, 24, a grandson of Peter Seibert Sr., was killed, and three others were injured in the out-of-bounds avalanche, the Eagle County Coroner's Office announced Tuesday evening.

Friends and family of Seibert's expressed sorrow and condolences throughout the afternoon and evening on social media.

Seibert was in a group with three others when the avalanche hit. The others, who were not identified, were rescued and treated for minor injuries.

Seibert's father is Peter Seibert Jr. His mother, Teri Salani Seibert, works for the Vail Ski Patrol, according to her Facebook page. It was unclear whether she was on duty Tuesday.

East Vail Chutes
The Eagle County Sheriff's Office released this image of the East Vail chutes area where one person was killed in an avalanche on Tuesday, January 7, 2014. (Eagle County Sheriff's Office)

In a statement, Chris Jarnot, Vail Mountain's senior vice president and chief operating officer, called the death "a shocking and terrible tragedy."

Jarnot added: "Our hearts, thoughts and prayers go out to Tony's entire family. I want to acknowledge how integral the Seibert family is to the fabric of our community. ... This is an incomprehensible loss and we will support the Seibert family and our community through this difficult time."

Vail Mayor Andy Daily expressed his sorrow on Twitter, citing the Seibert family's impact on the town over three generations.

The avalanche struck about 11:35 a.m. in East Vail Chutes, said Jessie Mosher, an Eagle County Sheriff's Office spokeswoman.

Rescuers and emergency workers responded to the area, which is between Vail Pass and Vail Mountain.

The Colorado Avalanche Information Center reported the incident shortly after 1 p.m., describing it as "large" and having happened at or near timberline.

Earlier, the CAIC rated the area at "considerable risk" for an avalanche, describing "dangerous avalanche conditions."

Its warning says: "Cautious route-finding and conservative decision-making essential."

There have been several fatalities in that part of East Vail over the past two decades. It is one of the deadliest resort-accessible areas for avalanches in the country, according to experts.

There were two avalanche-related deaths only days apart in early January 2008, and five deaths between 1986 and 1996.

On Dec. 22, skiers triggered two avalanches on steep east and southeast terrain of East Vail Chutes, also known as Charlie's Death Chutes. One of the avalanches trapped a skier before he was rescued by his brother.

Tony Seibert, who was a noted free-style skier in the Vail community, appeared in recent Warren Miller Entertainment productions.

East Vail Chutes
The Eagle County Sheriff's Office released this image of the East Vail chutes area where one person was killed in an avalanche on Tuesday, January 7, 2014. (Eagle County Sheriff's Office)

In Miller's "Climb to Glory," he appeared in a segment in which he followed the tracks of his grandfather's 10th Mountain Division.

Peter Seibert, who died in 2002 at the age of 77, served with the division, which trained in Colorado, during World War II.

He was part of the U.S. Ski Team and is credited, along with rancher Earl Eaton, as being the father of Vail Resorts, which opened in December 1962.

Tony Seibert and his co-star, ski-film veteran Chris Anthony, were planning to screen "Climb to Glory" on Thursday at Beaver Creek's Vilar Performing Arts Center as a benefit for Colorado Ski & Snowboard Museum education programs.

Anthony said involvement in the film had a deep impact on Tony Seibert.

"We got really focused, and he really started appreciating not just the blood lines that he came from but also the industry and the sport. He truly loved skiing. His heart was into it," Anthony said. "The movie, it really impacted him. It made him really proud."

Seibert had a solid ski background in both racing and freeskiing, able to move seamlessly between big mountain lines and terrain-park features and jumps. "Climb to Glory" was one of his first ski films.

"He was such a positive character on the shoot," Anthony said. "There was no ego. He was just glad to be a part of it."

Max Bervy, the director of "Climb to Glory," said Seibert and other descendents were equipped with 10th Mountain Division gear to make the film — a challenge for modern-day skiers used to water-resistant clothing, steel edges and wide skis.

"I think he really understood the significance of being a representative of a 10th Mountain guy," Bervy said. "He understood the significance that his grandfather had, not just in the Vail Valley but in the ski industry as a whole. It really resonated with him. Wow, my heart really aches for his family."

A member of the family noted Tony Seibert's death on Twitter at midafternoon. Nearly 200 messages of condolence were posted on his sister's Facebook page by early evening.

Tony Seibert, a 2008 graduate of Battle Mountain High School, graduated from the University of Colorado at Boulder in 2012.

Ryan Parker: 303-954-2409, rparker@denverpost.com or twitter.com/ryanparkerdp