A catastrophic storm described as a "once in 300 years" event has caused severe flooding in southern Thailand, resulting in at least 19 deaths and impacting over two million people.The city of Hat Yai in Songkhla province is the hardest hit, with floodwaters reaching beyond 2.5 meters, completely submerging more than 70,000 homes and cutting off Hat Yai Hospital from outside access.The Thai military and Thai Navy have mobilized large-scale rescue and relief efforts, deploying the HTMS Chakri Naruebet and working to pump water out of affected areas.