UT -A Flagstaff girl drowned in Padre Bay after carbon monoxide from the motor of a boat poisoned her Saturday at Lake Powell.

Megan Evans, 7, was swimming with her friend, Kayleen Tubbs, also 7, near two 30-foot cabin cruiser boats on the shoreline near their campsite, according to the National Park Service. Kayleen’s mother was showering using hot water from the boat motor when she noticed her daughter unconscious in the water.

She rescued Kayleen, who quickly regained consciousness. Megan was later found unconscious at the lake bottom Saturday, in water between 5 and 10 feet deep.

Both girls were flown to Page Hospital in Arizona, where Megan died. Kayleen recovered under oxygen treatments.

National Park Service authorities said the girls, both of Flagstaff, suffered poisoning from odorless, colorless carbon monoxide, which can collect near the swim platform of some boats.

Park rangers and the public have become more aware in recent years of the dangers of carbon-monoxide emissions from engines, a problem blamed for several deaths. In 2003, Utah passed laws requiring vessels to remain at least 150 feet from each other when at a cruising speed.

Megan’s death is the first such death in the Glen Canyon National Recreation Area, on the Arizona-Utah border, in five years.