More than a dozen people were injured, four critically, after a Santa Clarita city bus, a gravel truck, and a white sedan collided Wednesday morning at Centre Pointe Parkway and Golden Valley Road. The major crash prompted a massive emergency response, with 10 ambulances called to the scene as Los Angeles County Fire Department crews conducted triage. One person was trapped in the wreckage and had to be freed, according to The Signal . More than a dozen people were injured. KTLA 10 ambulances were called to the scene. KTLA One person was trapped in the wreckage and had to be freed. KTLA Authorities said the crash involved a Santa Clarita city bus, a truck, and a white sedan. KTLA Officials said all patients were transported from the scene by 10:17 a.m. The gravel truck was carrying a load at the time of the crash, spilling material across the roadway. At the time of publish, 13 people were injured — four suffered critical injuries while nine others sustained minor injuries.…