Explosion in the national park PHOTO/VIDEO

The hydrothermal explosion occurred in the Biscuit Basin geothermal area, known for its hot springs and geysers, not far from Old Faithful Geyser in Yellowstone National Park.

There were no reports of injuries, but the pool area was closed for the safety of visitors, AP reports.

Scientist Mike Poland of the Yellowstone Volcano Observatory said the explosion could be the result of a blocked passage in the geyser's water supply network.

"A clog would cause a build-up of heat and pressure, like what happens in a pressure cooker," Poland said.

He added that such eruptions occur periodically, usually when there are no visitors in the area. He also said that the largest known hydrothermal vent crater on Earth is in Yellowstone.

Scientists hypothesize that a series of hydrothermal explosions created the crater about 13,800 years ago in the Mary Bay area on the northeast side of Yellowstone Lake.

"What we saw was spectacular and definitely dangerous. But compared to what happened in Yellowstone in the past, this is minor, yet, it's a good reminder of the danger in Yellowstone," Poland said.

The explosion occurred at the "Black Diamond" geothermal source, known for its dark colors that resemble a black diamond.

Since 1890, at least 22 people have died from injuries related to geothermal incidents in and around Yellowstone National Park.

Visitors are regularly warned not to stray from the boardwalks and trails in the thermal areas.