Heat from the flames exceeded 2,750 degrees and caused the steel beams holding up the interchange from eastbound I-80 to eastbound Interstate 580 above to buckle and bolts holding the structure together to melt, leading to the collapse, California Department of Transportation director Will Kempton said.
Officials said that altogether a 250-yard portion of the upper roadway was damaged. The cost of the repairs would likely run into the tens of millions of dollars, and the agency was seeking federal disaster aid, Kempton said.
Witnesses reported flames from the blaze rose up to 200 feet into the air. The charred section of collapsed freeway was draped at a sharp angle onto the highway beneath, exposing a web of twisted metal beneath the concrete. 