Officials said the fire, which had spread to more than 500 acres by Thursday night, was miles away from threatening any homes or buildings.

A wildfire in the hills near the U.S.-Mexico border exploded early Friday morning over thousands of acres, prompting evacuation orders throughout the Otay Wilderness Area and triggering school closures as well as likely power shutoffs for tens of thousands of people.

U.S. officials say the Pentagon will begin deploying as many as 1,500 active duty troops to help secure the southern border in the coming days.

The move enacts President Trump's executive orders issued shortly after he took office to intensify immigration enforcement.