Multiple reports say a U.S. Marine goes missing during a training exercise off the southern California coast, prompting a search by the U.S. military and other agencies. Coverage from ABC News, The Independent, the Los Angeles Times, and the Oregonian reports that the Marine is missing near the San Diego area, with search efforts beginning early Thursday, shortly after midnight, and involving several units and organizations. The reports describe the incident as occurring during a routine training operation at sea off the coast. The New York Post adds additional detail, stating that a San Diego-based Marine dies after being declared lost at sea, though it does not contradict the overall account that the Marine went missing during the training. Other outlets emphasize the ongoing search and do not focus on final status in their summaries. Overall, the information agrees that the incident involves a Marine from the San Diego region who is last seen during training at sea, and that authorities coordinate multi-agency search efforts off the coast of southern California.