joshua tree national park

Park officials said few rangers are on hand to prevent off-road driving, which causes destruction of the park's namesake trees. Volunteers have been cleaning the nearly 800,000-acre park.

Volunteers and a skeletal staff have maintained sites in some parks. In others, the amount of damage and trash triggered an unprecedented move from the National Park Service to return more workers.

Rescue crews have been combing the park since the couple was reported missing on Friday, but several rescuers have been overcome by the heat themselves.