Thirty-four vehicles, including four semi-trailer trucks, were involved in a chain-reaction pile-up Monday morning in Colorado that temporarily shut down a major highway and sent 12 people to area hospitals, state police said. The massive accident occurred on Interstate 25 northbound in Larkspur, about 40 miles south of Denver and 30 miles north of Colorado Springs, Colorado, State Patrol Trooper Nate Reid told CNN. None of the injuries appeared to be life-threatening, according to Reid. He added that road conditions were icy and wet at the time of the accident.