Several dogs were struck by vehicles traveling in both directions on the roadway.
Several Good Samaritans stopped on the roadway to try to help rescue the dogs.
Witnesses said a white van stopped on the side of the road and let 15 dogs out of the vehicle at about 6:30 p.m. The location is in the vicinity of a popular dog park.
El Segundo Police were called to the scene. It was unclear how many dogs were rescued, injured or killed.
A $5,000 reward was offered for information leading to the arrest of the individual(s) responsible for the incident. If you have information about the incident, contact El Segundo Animal Control (310) 524-2231.