The Kochi International Airport has been temporarily closed and two flights diverted as the runway got water-logged. Periyar river and canals are overflowing after the downpour lashed the area since yesterday.
The deceased included two children and two women as their houses on the slopes of the hills in Idukki district were swept away by flash floods, police said.
A district where most people are small and marginal farmers, Idukki also suffered heavy crop and property loss.
Several persons were reported missing as a huge mound of rock and rubble came crashing down at Chiyyappara in Idukki while relief work was on in the area where landslip occurred in the wee hours.
Several vehicles were trapped in the debris and rescue work hampered as roads the district got blocked by rubble spawned by landslide and flashfloods.
"Cochin International Airport has been closed till 2.30 PM as water entered the runway as the Periyar river is overflowing after shutters of the Edamalayalar dam were opened," Airport Director ACK Nair told PTI.
The sandbanks of the Periyar river in Aluva, where thousands are to converge to perform the Balitharpanam ritual tomorrow on the day of Karkitakavavu, is flooded and the Shiva temple there almost submerged.
Ernakulam District Collector Sheikh Pareed said possibilities of making alternative arrangements for the conduct of the ritual were being explored and the help of Navy sought to tackle the situation.
People in affected areas have been shifted to relief camps.
Chief Minister Oommen Chandy has called an emergency cabinet meeting in the state capital to review the serious situation and gear up the relief operations.
The IMD has cautioned fishermen not to venture into the sea in the next 48 hours as strong winds of 45-55 kmph could lash coastal areas along with heavy rains.
The Southern Naval Command has sent two teams comprising 20 divers and four rubber inflatable boats, to the island of Thuruthu at nearby Aluva in Ernakulam district to provide assistance to marooned families.
Another team is being sent to Idukki district to provide suitable assistance at the site of the landslip.
All the teams are being sent on specific request from the State administration, a Naval press release said.
Meanwhile, relief camps have been opened in six taluks-- Paravur (15), Aluva (8), Kothamangalam (8), Muvattupuzha (2), Kunnathanadu (3) and Kanyannur (1) all in Ernakulam district, district administration sources said.