The crash happened Thursday evening when a white SUV collided head-on with a semi truck near the 405 Freeway, according to the Los Angeles Fire Department.
Six people were inside that car, including the children. One person who firefighters were trying to extract from the SUV was pronounced dead. The children were taken to a hospital in unknown condition.
One person, believed to be the driver, was hogtied and taken into custody on the freeway. According to the California Highway Patrol's traffic log, officers Tased that man because he was uncooperative.
It's not clear why he was driving in the direction of oncoming traffic.
CHP said the person who was killed was a woman. Her name has not been released.
All southbound lanes were reopened after 1 a.m. Friday.