Hundreds of people were rescued as severe flooding batters Hawaii’s Oahu island, prompting evacuation orders near a dam officials feared could overtop as water levels rose.

Gov. Josh Green said conditions on Oahu’s North Shore were “very serious” early Friday as heavy rain triggered rapid flooding, prompted evacuations, and led to multiple rescues.

Muddy floodwaters from severe rains have inundated communities and prompted evacuation orders for more than 5,500 people in towns north of Honolulu. Officials are warning about the possible failure of a 120-year-old dam.