Thousands of residents have fled the town that hosts the Los Alamos nuclear laboratory ahead of a wildfire that has charred more than 20,000 hectares (49,000 acres) in northern New Mexico, local authorities said Tuesday.

Los Alamos, a town of some 13,000 inhabitants, is the site of the national laboratory where the United States' first atomic bombs were manufactured and tested.

The fire is at least 5 kilometers (3 miles) from the lab's Area G, where tanks of radioactive waste are stored before being taken to the Waste Isolation Pilot Project site in Carlsbad, New Mexico.

The Los Alamos County fire chief, Doug Tucker, told the press that on Monday residents evacuated the town in an orderly fashion after the blaze, which broke out over the weekend, crossed the nearby Jemez Mountains.

In a single day the flames, swept along by winds of up to 95 kph (60 mph) and fueled by the dry trees and bushes of the forests, crossed the Pajarito Mountain Ski Area, and Tuesday morning authorities tried to determine if the wildfire had reached Pajarito Canyon.