Authorities in Japan have warned people not to go up Mount Fuji before it's safe to do so. They've seen four climbers die at a time when the trails are still closed to hikers.
Police responded to a call on Sunday morning from a Tokyo resident who couldn't get in touch with her 53-year-old husband after he went to climb Mount Fuji.
Police went to look for him and found three people in a state of cardiac arrest near the crater on the south side of the peak.
The climbers were found separately at different locations. Police are working to identify them and determine how they died.
On the north side, a 38-year-old man collapsed and fell unconscious on Wednesday. He was taken to a hospital and confirmed dead there.
The three trails from Shizuoka Prefecture and one from Yamanashi Prefecture don't open for the season until July. But that doesn't stop some people from going up the mountain.
Takekawa Shunji, a mountain guide at home and abroad, explained the challenges in climbing Mount Fuji.
He said: "Mount Fuji in winter is classified as one of the toughest mountains for winter climbing in Japan. Conditions are so severe that people with just some experience with ordinary mountains in winter can't deal with it. It still has some snow in June, so a climber must know that conditions won't be different to those of winter."
Overnight lows at the peak at this time of year dip below freezing some days and patches of snow remain.
Shizuoka officials check and repair their climbing trails before the season opens. But proper maintenance work can't be done when the trails are closed. Many lodges are shut, as are aid stations.
Officials point out that climbing the trails out of season is dangerous. They are urging people not to try it.