Mr Sasendran said at least 66 people were being treated at local hospitals for injuries, adding that hospital staff were among those missing in the landslide.
Wayanad, a hilly region that is part of the Western Ghats range, is prone to landslides during the monsoon season.
The landslides hit several districts in the region, including Mundakkai, Attamala, Choorallmala and Kunhome.
A bridge linking Chullalmala, Mundakai and Atamala collapsed, isolating the two areas and making it difficult for rescuers to reach trapped families.
State and national disaster relief teams are working to rescue the victims. Several local residents are also helping.
Prime Minister Sasendran also said he had asked the army and air force to airlift trapped families and build a makeshift bridge.
Wayanad district and nearby areas are on alert due to forecast heavy rains.
Schools and colleges are closed in 10 of the state's 14 districts.
In 2019, a landslide killed 17 people in Puttumala, Wayanad, about 10 km from the current affected area.
Prime Minister Narendra Modi posted on X (formerly Twitter) that he had spoken to Kerala Governor Pinarayi Vijayan and assured him of the federal government's help in relief efforts.
Prime Minister Modi also announced compensation of 200,000 rupees ($2,388, £1,857) to the victims' families and 50,000 rupees to the injured.
Additional reporting by Ashraf Padanna in Trivandrum, Kerala
