Fallen Yosemite climbers were 'very experienced'
Family and officials are baffled by the deaths of two "very experienced" rock climbers who fell to their deaths in Yosemite National Park on Saturday.
Jason Wells, 46, and Tim Klein, 42, had climbed together for decades, including in the California park.
Officials are investigating how they both fell over 1,000ft (300m) from the granite rock formation, El Capitan.
Yosemite Climbing Association president Ken Yager said: "Something weird happened. There's no doubt in my mind."
He told the New York Times the two climbers had been using a technique that allowed them to increase their pace.
"I've been worrying about this speed game for a while," said Mr Yager.
"The faster you go the more dangerous it is."
The US National Park Service said the two friends fell from Freeblast, a vertical route up El Capitan.
Mr Wells and Mr Klein had been friends since meeting at university in San Diego, according to widow Jennifer Klein.
"I know that he was well loved and made a huge impact in people's lives," she told CBS News of her husband.
"They loved each other like brothers."
Mr Klein, who taught at the Palmdale High School in California, had recently won the teacher of the year award from his school district for the second time.
According to Climbing magazine, in 2014 Klein climbed at an indoor gym for more than nine hours in an effort to raise money for a student who had been paralysed in a drive-by shooting.
The father of two boys had climbed for a total of 29,065ft - higher than Mt Everest - and broke a Guinness Record in the process.
Mr Wells, an asset fund manager from Colorado, is survived by his wife and daughter.
Wayne Willoughby - a friend of both men - told Climbing magazine that the accident occurred on what would have been Mr Klein's 107th trip to El Capitan.
He added that the two friends had climbed together in Yosemite dozens of times over the years, and had been known to scale the 3,000ft megalith twice in one day.
"Tim told me that Jason was the strongest and best partner he ever climbed with," Mr Willoughby said.
How did they fall?
The two mountaineers had been roped together when they fell, local climbing experts say.
They had been moving through a relatively moderate part of the route using a technique called "simul-climbing" (simultaneous climbing) when they fell, said Brady Robinson of the Access Fund, an outdoor rock climbing organisation.
He explained the technique is "inherently riskier" than regular climbing, because it allows the group to move at a faster pace.
A third person who has not been identified by officials was also present during the climb but did not fall, he added.
"He didn't see what happened - he came to the top of the rope and his partners were gone. He didn't witness it," Mr Robinson told the New York Times.
According to Climbing magazine, this is the 25th death of a climber recorded on El Capitan.
The popular climbing destination sees more than 100, mostly non-fatal, accidents each year.