Four hospitalized after rocks fall at Red Rocks

Seven people were hurt over the weekend -- and four hospitalized -- when rocks fell on the crowd in a section of the Denver area's iconic Red Rocks Amphitheater.

According to local reports, at least six rocks fell from a large formation on the natural amphitheater's north side dubbed Creation Rock, falling on people who were on a stairway. No information was immediately available on the severity of the injuries

The incident took place at about 1 a.m. on Sunday (9/11) as Sound Tribe Sector 9 was wrapping up its encore. The band reportedly played two sold-out shows at the venue over the weekend.

Investigators are looking into the incident, but so far haven't determined its cause. According to reports, witnesses saw people climbing on the rocks before the rocks fell.