Rock slide leaves boulders on Interstate 70 in Glenwood Canyon near Glenwood Springs, Colorado

Large boulders tumbled down Glenwood Springs Canyon during a rock slide and slammed into two semi-tractor trailers on Interstate 70 Monday night, authorities said. The drivers of the two semis were not injured in the rock slide that damaged the highway, said Nate Reid, spokesman for the Colorado State Patrol. "Smart-car-sized boulders fell down canyon walls," said Amy Ford, CDOT spokeswoman. A 24-mile stretch of I-70 between Gypsum and Glenwood Springs was closed following the 9:04 p.m. rock slide, according to the Colorado Department of Transportation.