Two cars racing each other on Route 1 in Edison Thursday afternoon led to a four-car crash that left one person seriously injured and traffic snarled for hours, authorities said. One of the racing cars hit a third vehicle and ultimately resulted in a four-car crash, Edison Police Chief Tom Bryan said Thursday afternoon. One of the cars fled the scene and police were searching for the car later Thursday, according to Bryan. There were no fatalities in the crash, Bryan added. Traffic on Route 1 was still backed up at 5 p.m. as police investigated the crash, authorities said. There was no update …