Page, Arizona (Associated Press) — The National Park Service said Friday that investigators ruled a fire that destroyed several houseboats on Lake Powell, a popular destination on the Utah-Arizona route, was an accident.

However, the park service said in a statement that the source of the fire that broke out at Waweep Marina last week has yet to be determined.

Officials said photos and videos of witnesses helped investigators come to a conclusion.

The fire broke out in the early afternoon of June 2 as tourists were enjoying the lake. It started on one ship and then spread to others.

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Photos and videos posted online showed black smoke billowing over the lake and the red rock walls that formed its perimeter.

Firefighters from multiple agencies were able to extinguish the fire by evening.

Two people were treated at the scene for smoke inhalation, the Parks Service said. There were no other injuries.

After that, the area around the wharf was closed to the public, but it was reopened.