KUSA - An avalanche "in-bounds" was reported Saturday just before 3 p.m., in West Montezuma Bowl. That is on the back side of Arapahoe Basin.
The slide happened in terrain that's in-bounds, but closed to the public.
An A-Basin ski patroller was leading a group of 14 people in that area when they got caught in the slide.
Everyone is accounted for, but one person hurt their knee.
The A-Basin ski patrol says it has done extensive avalanche mitigation and explosive work in that same area over the last week.
The ski area and the Colorado Avalanche information center are investigating.
Another in-bounds avalanche at A-Basin nearly eight years ago killed a Boulder man.
In May of 2005, 53-year-old David Conway got trapped in the sliding snow on the Pallavicini Trail, an expert run.
That slide was 800 vertical feet and and about 200 feet wide.
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