A white Honda sedan was struck in the rear by a gray pick-up truck which then struck another pickup truck in the southbound lanes of I-15 approximately 1 mile south of the Rainbow Valley on ramp to I-15. All lanes of the southbound I-15 were completely shut down by the California Highway Patrol for about 40 minutes. One person was injured and transported to Palomar Medical Center. The extent of their injury is unknown at this time. The cause of the accident remains under investigation and it is unknown if alcohol and or drugs were a factor. No further information is available at this time.