YOSEMITE NATIONAL PARK — One day after a huge rock slide from El Capitan in Yosemite National Park killed a British man and injured his wife, another slide, larger than the first, rocked Yosemite Valley Thursday afternoon.

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Yosemite: Hazardous smoke, fire closure. Oh, and biting snakes. Park officials announced that the slide, which sent a huge plume of dust across the valley, had closed Northside Drive, the main road out of Yosemite Valley. At least one person was injured by the 3:21 p.m. slide and airlifted to a hospital for treatment.

Two Norwegian rock climbers told a Bay Area News Group reporter that they were walking on a trail and about to begin climbing a nearby rock when they both heard an ominous noise.

“It was a thundering sound. I didn’t know what to think,” said Hennette Olsboe Froeyen, 27, from Bergen, Norway, who took a photo of the slide.

“Then we quickly got out of there because we didn’t know if it would continue,” she said.

Her boyfriend, Simon Fonn Storevik, also from Bergen, said, “You could hear from the sound that it was something very massive.”

The couple said they had planned on rock climbing in the area of the slide Thursday afternoon and would have been there had they not missed an exit getting to Yosemite.

A day earlier, parts of a slab that was 130 feet high and weighed 1,300 tons fell from El Capitan.

That slide, which occurred with at least 30 climbers on the iconic granite wall, was one of seven rock slides over a four-hour period starting at 1:52 p.m. Wednesday, said Yosemite spokesman Scott Gediman.

The slab of rock, which was about 65 feet wide and up to 10 feet thick, came down in pieces and fell from a location about 1,800 feet above the valley floor, park officials said.

The park remains open, and climbing has not been restricted.

A 32-year-old man who died in Wednesday’s rockfall at 1:52 p.m. has been identified as Andrew Foster of Wales. His wife, who was not identified, was airlifted to a hospital where she was being treated for serious injuries.

“They were walking around the base of El Capitan,” Gediman said. “We think that they were climbers and they were not climbing yet. They might have been scouting.”

From his post two miles away, Gediman said Thursday’s rockfall sounded like a “roar.” Exact figures were not immediately available, but the slide was “significantly larger” than the one Wednesday.

After Wednesday’s rockfall, climbers posted pictures on social media.

“I saw a piece of rock, white granite the size of an apartment building, at least 100 feet by 100 feet, suddenly just come peeling off the wall with no warning,” said Canadian climber Peter Zabrok, 57, who was scaling El Capitan and was above the rockfall.

One of the most iconic features of America’s national park system, El Capitan rises 3,600 feet above the valley floor on the north side of Yosemite Valley. The sheer granite wall, carved from glaciers a million years ago, is an internationally famous rock-climbing destination.

The granite features that make Yosemite a destination for more than 4 million visitors a year are not frozen in time. They are ever-changing, and rockfalls are common. But fatalities are rare.

“We have about 80 (rockfalls) reported in the valley each year,” Gediman said. “I hear them all the time. Most of them are smaller. They happen year round. Yosemite National Park is a wild place by definition. We’ve had larger ones than this.”

A rockfall on the July 4th weekend in 2015 peeled a slab off the iconic face of Half Dome. The piece was roughly triangular, more than 200 feet on its longest side, and estimated at 2,400 tons. Nobody was injured in that incident, though it was on the popular Regular Northwest Face route. A rainstorm earlier in the day had driven most climbers away.

The last person killed in a rockfall at Yosemite was Peter Terbush, a 21-year-old college student from Colorado who was killed when rocks fell from Glacier Point on June 13, 1999.

Standing on the ground, the rock climber was anchoring a climbing partner’s rope when 525 tons of boulders fell from 1,300 feet above. Terbush did not run away. Instead, he held the rope tightly, saving the life of his friend, Kerry Pyle, who was 60 feet above. Hailed as a hero afterward, Terbush was killed when a chunk of rock hit him in the head.

His family sued the National Park Service for negligence afterward for $10 million, saying that the park should have posted warning signs and may have increased the risk of danger because water from a leaking storage tank at Glacier Point could have affected the rock’s stability. A judge dismissed the lawsuit in 2005.

In 2003, a rockfall near Curry Village damaged several cabins and injured four people. About 100 cabins closed afterward. Some were relocated.

There have been 16 fatalities in Yosemite and more than 100 injuries from rockfalls since park records began in 1857.

Gediman said that visitors to the park are not in danger, and that most trails, roads and buildings are out of the zone where rocks fall. However, signs about the recent slide activity have been posted.

“People should not worry about coming to the park,” he said. “But we suggest that they be aware of their surroundings. We’ve had some trees fall due to bark beetles. When you are near water, be aware of that. Rock walls are the same thing.”

Ken Yager, president and founder of the Yosemite Climbing Association, reviewed photos of the cliff face and debris field, estimating that the relatively thin piece that broke off Wednesday covered an area big enough to fit several houses.

“It cratered and sent stuff mushrooming out in all directions,” Yager said.

Zabrok said he and friends were in the middle of a six-day climb of the Waterfall route on the right side of El Capitan when they saw it.

“Boy, I don’t know how anybody could have survived that,” he told KFSN-TV, the ABC affiliate in Fresno.

Peering down from his perch 2,000 feet up on the rock, Zabrok said he saw a rescuer lowered by helicopter and “I believe he grabbed one survivor.”

The rescuers also were in danger, he noted.

“It was done at tremendous peril to the rescuers because there were three subsequent rockfalls that were all nearly as big and would have killed anybody at the base,” he said.

Climber Kevin Jorgeson said he and climbing partner Tommy Caldwell witnessed a massive rockfall in the same area while they prepared for a trek that made them the first people to free-climb the Dawn Wall on El Capitan in 2015.

A study earlier this year found that the hottest hours of the day — during the hottest months of the year — are prime time for unexplained rockfalls and cracking in the Sierra Nevada.

Brian Collins, with the U.S. Geological Survey, and National Park Service geologist Greg Stock looked at the pattern of 228 past rockfalls in Yosemite with no known cause and found that about 15 percent occurred in the hottest hours of day, from noon to 6 p.m, between July and September. If the rockfalls were random, only 6 percent would have happened during those hours, days and months.

While rock movement is most profound in heat, it happens all year long, Collins said. And other things — such as winter rain and snow, even tree roots or lightning strikes — may actually trigger the final collapse.

Since the glaciers retreated around 15,000 years ago, rockfalls have been the major force of change in the Sierra Nevada.

“People look at landscape as static, that it will be there forever,” said Collins. “But it’s changing all the time.”

Staff writer Jason Green and The Associated Press contributed to this report.