(Portland, OR) -- A Portland-based doctor is speaking out about his experience providing first aid to the victims of Monday's deadly Amtrak train derailment. Dr. Nathan Selden with OHSU Doernbecher Children's Hospital tells KOMO News he was heading to Seattle with his son when the train derailed, sending several cars tumbling onto southbound I-5. Selden immediately jumped into action, administering first aid to wounded passengers for two hours. Selden called the crash catastrophic, saying it was the worst emergency he'd ever seen.