Footage shows tourists running for their lives amidst hydrothermal explosion in Yellowstone

Earlier this week, a hydrothermal explosion in Yellowstone National Park sent terrified visitors running for safety.

On Tuesday (July 23) at 10am local time, an eruption of scorching water, steam and debris shot up into the sky at Biscuit Basin, a collection of hot springs about two miles northwest of the famous Old Faithful Geyser.

Vlada March, from California, was visiting the park with her family when the explosion happened.

In video footage shared to Facebook, dozens of visitors can be seen moving off a boardwalk next to the hot spring as March yelled at her family to 'run.'

Others can be heard shouting "Back up," and "Holy cow."

Alongside the video, March wrote: "Biscuit Basin at Yellowstone National Park just exploded right in front of us.

"Boardwalk destroyed, my mom got some of the debris but everyone is safe. Unbelievable and grateful to be alive."

She also shared a clip of the aftermath of the explosion, showing the area flooded with water as well as the damaged boardwalk.

The National Park Service has since cut off access to the area 'for safety reasons' while geologists investigate the event.

The United States Geological Survey (USGS) confirmed that a small hydrothermal explosion had occurred in the Biscuit Basin thermal area.

This happens when when water at or near boiling point beneath the ground rapidly turns into stream because of a drop in pressure.

Ken Sims, a geology professor at the University of Wyoming, said that it's similar to the steam that builds up inside a pressure cooker.

"Eventually it’s going to get so much steam that it’s going to pop."

A hydrothermal explosion at Yellowstone National Park sent visitors running for their life on Tuesday (Facebook/Vlada March)

He continued: "These explosions are common — that’s what makes Yellowstone so special. If magma were involved there’d be far more ground deformation, gas emissions and all around changes, whereas this is an isolated pocket of steam that caused the ground to explode."

Following yesterday's explosion, the National Park Service said it hasn't detected any other changes in the Yellowstone region so there's no need to worry about any imminent volcanic eruptions.

"Today’s explosion does not reflect a change in the volcanic system, which remains at normal background levels of activity," the agency shared in a statement.

And the USGS said: "Hydrothermal explosions like that of today are not a sign of impending volcanic eruptions, and they are not caused by magma rising towards the surface."

It's not currently known when the boardwalk will reopen.