There were no fatalities in the blasts, said police spokesman Officer Willy Kerin. Seventeen people suffered minor injuries, including one firefighter who suffered an asthma attack.
"We were just very lucky," Kerin said. "We take it for granted, but He was on our side this evening."
The pickup, parked at a gas station, rolled across the street to the Cortez Gas Co. and struck an 18,000-gallon propane tank about 8 p.m. Sunday, state police spokeswoman Royleen Ross-Weaver said.
The explosion fueled a blast in a second tank holding 2,000 gallons of the flammable gas, police said.
"About 4 or 5 structures did catch fire plus a lot of plate glass windows were broken throughout the town," Dixie Fisher, director of Sierra County Regional Dispatch, told CBS Radio News.
Police were seeking the vehicle's owner, who apparently left the scene after the blasts.
Former CBS Radio News editor Gayle Combest reports the explosion occurred "on the same street as our only stoplight.
"There was just one huge explosion," he said, "and of course we looked out the windows immediately, and (there was a) huge, flames, and we are 15 blocks away."
Kerin said several minutes elapsed from the time the pickup struck the tank and the first blast, and another several minutes elapsed before the second explosion, giving some 200 residents time to flee.
"It was just an instinct to get people out," said Kerin, one of the first officers on the scene. "Once I got there, there was a very large cloud of gas and the propane was coming out of the tank, and, seeing it, I just put it in reverse and started calling for help. I never backed up so fast in my life."
Kerin estimated four or five mobile homes burned to the ground.
"We had damage done to other areas of the city from the tremors that went through," he said. "This is very devastating."
Firefighters Rudy Flores, 20, and his cousin Henry Flores, 18, were rushing to the scene when the first explosion hit.
"When we turned the corner, they told us to hold back and all of a sudden it goes boom, a big old explosion. It was crazy," Rudy Flores said.
"It busted out all the windows two blocks down," Henry Flores added.
Windows at the nearby Shell station blew out and the plastic coverings on the fuel pumps melted.
Firefighters controlled the blazes in two hours, Kerin said.
Most of the damage was sustained in an area of about three city blocks - an industrial section about a half mile (800 meters) northeast of downtown and part of a sparsely populated recreational vehicle park.
Early Monday, smoke rose from the area, which was scattered with debris and surrounded by charred trees.
Domenica Rush, the aministrator at Sierra Vista Hospital, said injuries were mainly from smoke inhalation and minor burns.
Stunned residents wandered near the area late Sunday, asking police when they would be allowed to return home.
Evacuated residents were taken to makeshift shelters set up by the Red Cross and other groups. Some were offered rooms at area hotels.
The town, 150 miles south of Albuquerque, has about 6,200 residents.
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