Published: Aug 24, 2011 3:28 PM EDT

LINCOLN, Calif. (AP) - Fire officials say the risk of an explosion at a rail car fire in Northern California has increased after the propane tank that is burning showed signs of melting and coming apart.
    
California Department of Forestry and Fire Protection spokesman Daniel Berlant told KCRA-TV on Wednesday that firefighters have not been successful in cooling the 29,000-gallon tanker with water. The fire began a day earlier at a Northern Propane Energy yard in Lincoln, a city of 40,000 north of Sacramento.
    
Berlant says a crack in the tanker would greatly increase the possibility of an explosion.
    
That possibility has led to the evacuation of thousands of homes in the area. Fire officials say an explosion could cause a fireball that consumed blocks and hurl large pieces of metal up to a half mile away.

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