A helicopter crashed into the Han River near Gangdong Bridge on Saturday, leaving one dead and two injured.
Firefighting authorities rescued the two pilots, but a mechanic on-board was found dead over an hour after the chopper crashed.
The two pilots were transferred to hospital and are said to have minor injuries.
Police say the Korea Forest Service helicopter crashed at around 11:20AM local time.
The helicopter was on an operation to collect water from the river to put out a fire in the northeastern part of Seoul.