Nearby hill crumbled to houses of the labourers in the plantation in Nemakkad area of Idukki.
Three housing complexes have been swept away.
Eleven dead bodies have been recovered till now. Nearly 78 persons are believed to be trapped.
12 people have been admitted in hospital.
The complex was housing more than 80 labourers.
The state government has rushed a 50-member team comprising fire service personnel from Kochi and 15 ambulances to the site.
Two teams of the NDRF are in Idukki for the rescue and relief operations.