Some 180 were reportedly injured and 200 went missing. The tragedy occurred in the early hours of Saturday.
According to the Noticias Caracol broadcaster, heavy rains in the country led to rivers bursting their banks, flooding hundreds of homes with mud in the city of Mocoa in Putumayo province, bordering Ecuador and Peru.
Mocoa is the capital of the Putumayo province. The city was populated by some 42,000 people as of 2015. A state of emergency was declared. Some 2,500 people including 800 police officers and 1,400 soldiers are working on the scene. A rescue plane has been sent to the area. The landslide totally destroyed three districts and severely affected 14 others.
"The houses were erased in practically 17 neighbourhoods," mayor Jose Antonio Castro said.
Con dolor, lamento el fallecimiento de compatriotas, en una avalancha anoche en Mocoa, Putumayo. Viajo esta mañana a la zona.— Juan Manuel Santos (@JuanManSantos) 1 апреля 2017 г.
With pain, I regret the passing of compatriots, in an avalanche last night in Mocoa, Putumayo. I travel this morning to the area, President Juan Manuel Santos wrote.