According to the L.A. news, the explosion at the Santa…

““According to the L.A. news, the explosion at the Santa Monica beach had been caused when a crazy kidnapper fired a shotgun at a police car. He accidentally hit a gas main that had ruptured during the earthquake. This crazy kidnapper (a.k.a. Ares) was the same man who had abducted me and two other adolescents in New York and brought us across country on a ten-day odyssey of terror. Poor little Percy Jackson wasn’t an international criminal after all. He’d caused a commotion on that Greyhound bus in New Jersey trying to get away from his captor (and afterward, witnesses would even swear they had seen the leather-clad man on the bus—“Why didn’t I remember him before?”). The crazy man had caused the explosion in the St. Louis Arch. After all, no kid could’ve done that. A concerned waitress in Denver had seen the man threatening his abductees outside her diner, gotten a friend to take a photo, and notified the police. Finally, brave Percy Jackson (I was beginning to like this kid) had stolen a gun from his captor in Los Angeles and battled him shotgun-to-rifle on the beach. Police had arrived just in time. But in the spectacular explosion, five police cars had been destroyed and the captor had fled. No fatalities had occurred. Percy Jackson and his two friends were safely in police custody.””

— Rick Riordan