LOS ALAMOS, N.M. (AP) - Fire officials battling the Los Alamos wildfire say they determined that a tree falling onto power lines sparked the blaze.
The fire erupted June 26 and has since scorched 189 square miles, or about 121,000 acres, of land northwest of Santa Fe. It is 19% contained.
Until Sunday, officials hadn't released a cause of the fire, which initially caused alarm as it burned close to the Los Alamos Nuclear Laboratory.
Los Alamos and nearby communities were evacuated nearly a week ago, but about 12,000 residents were allowed to go home Sunday.