Several people were seriously injured in a four-vehicle collision at a busy coastal North County intersection late Friday afternoon. The pileup at El Camino Real and Cannon Road in Carlsbad was reported shortly after 4:30 p.m., a dispatcher said. The wreck left traffic lanes blocked by damaged cars, pickup trucks and emergency vehicles, and led to heavy rush-hour congestion in the area. According to police, a 1999 Honda Civic driven by a 37-year-old female collided with three other motor vehicles. A preliminary investigation has revealed that the Honda was driving westbound Cannon Road. Two other vehicles, a Dodge Ram and Chevrolet Corvette, were travelling northbound El Camino Real when the Honda entered the intersection and collided with the Dodge Ram and Chevrolet Corvette. The Honda and the Dodge Ram then travelled west where the Honda collided with a Chevrolet Silverado pickup that was stopped in the southbound El Camino Real turn lane waiting to turn eastbound onto Cannon Road. One of the drivers was transported via helicopter to Scripps La Jolla and one other was transported by ambulance to Palomar Hospital where they were treated for their injuries. One of the injuries is possibly life threatening.