U.S. President Joe Biden has toured areas of Maui devastated by recent wildfires and where more than 1,000 people are still missing, calling it an "unimaginable tragedy,” as he seeks to reassure residents frustrated by his handling of the disaster.

"Whatever you need, you’re going to get,” Biden said Monday in the historic town of Lahaina, which was ravaged by the fires, vowing to help residents rebuild. "To the people of Hawaii. We’re with you for as long as it takes. I promise you.”

Biden, joined by first lady Jill Biden, saw firsthand the effects of one of the worst disasters to strike the U.S. during his administration. Federal estimates put the damage at more than $5.5 billion.