Two more climbers died Friday on Mount Everest, becoming the eighth and ninth people to die there since last week. That's more than all of last year.

The deaths come amid massive crowding near the summit of the world's highest peak.

It's a human traffic jam at the top of Mount Everest as hundreds of climbers wait hours for their chance to stand at the top of the world. Lukas Furtenbach reached the summit Thursday, he's still climbing down.

"It was very crowded," Furtenbach said. "We are here every year and I've never seen such a year. We lost about three hours waiting at the most difficult part of the rock."

Climbers call the area above 26,000 feet the "death zone," because the air is so thin. Most need supplemental oxygen.

"And that's very dangerous if you run out of oxygen, you can die within a couple of hours," Furtenbach said.

So far this season, at least nine climbers have died on everest, more than all of last year. Almost all died coming down from the traffic jam at the summit.

Experienced Everest climbers said it's particularly busy this year, because weather conditions provided only five days where the skies were clear enough to summit.

"Everybody is sharing weather forecasts," said Alan Arnette. "And in the end everybody goes for the summit at the same time."

Arnette climbed everest in 2011 and he now chronicles climbers on his blog

"The human body was not designed to survive above 26,000 feet," Arnette said. "You are just getting weaker my the minute. So in that respect the crowds are certainly a contributing factor to these deaths."

Most of the bodies will remain on Mount Everest — a solemn reminder to future climbers.