LOS ANGELES (AP) — An explosion at an industrial park near Los Angeles has injured four people, three of them critically. Authorities say it happened in a Santa Clarita neighborhood at about 4:45 p.m. Tuesday. The blast left three men with severe burns and they were taken to a hospital in critical but stable condition. A fourth man later walked into the hospital for treatment. The blast was initially reported as being on a movie set. The region has been used for filming but none was taking place at the time. The explosion sparked a small brushfire that was quickly contained.