The agency says two people died in landslides, and a child was killed when a tree fell on a car outside a school in Panama City.
Panama announced today it was cancelling classes it began to release water from locks and lakes feeding the Panama Canal.
Otto is gained strength in the Caribbean and could become a hurricane soon as it heads for a possible Thursday landfall in Costa Rica or Nicaragua.
The US National Hurricane Center in Miami says the storm has top sustained winds of 110 kph and is stationary about 420 kilometres east of Limon, Costa Rica.