During the pre-dawn hours of 1 April 2017, locally heavy rain triggered flash flooding and landslides in the city of Mocoa, Putumayo, Colombia, killing at least 336 people, injuring 400, and leaving 200 others missing.

[5] Throughout much of the first three months of 2017, the northwestern coast of South America saw above-average rainfall, leading to deadly floods in Peru and Ecuador.

During the evening hours, a slow-moving mesoscale convective complex developed within this region and produced heavy rainfall in southern Colombia.

With the system moving perpendicular to tall mountains, orographic influence likely enhanced rainfall and further contributed to the subsequent disaster.

[8] Numerous poorly constructed homes were leveled, and large portions of the city were left buried in several feet of mud.

[4] The disaster adversely affected 17 of the city's neighborhoods, with the mayor of Mocoa, José Antonio Castro, stating some areas "[had] basically been erased".

[15] The Colombian Red Cross activated its National Crisis Room in response to the disaster and deployed a team of 47 people to assist in recovery.