At least 20 people have died after Cyclone Gaja made landfall in southern India on Friday morning, bringing heavy rain and winds of up to 125kmph (75mph).

More than 80,000 residents had been evacuated from low-lying areas on the eastern coast of Tamil Nadu state, the local government said, but Gaja hit with the force of a severe cyclonic storm.

Gaja has since weakened to a cyclonic storm and is passing across the southern tip of India to the west, a bulletin from the Indian Meteorological Department. It is likely to weaken into a “deep depression” by Friday night as it brings heavy rain to Kerala before moving off into the Arabian Sea.

Those who died were mostly killed by trees uprooted by the strong winds, or collapsing roofs and walls. A three year old boy was believed to be the youngest killed, at Adiramapattinam, while a A 67-year-old retired man died when he was hit by a falling tree in Pulangudi.

Schools have been shut across the state and with rough seas, fishermen have been advised not to enter the Bay of Bengal since Sunday. More than 470 relief centres have been receiving evacuees across six districts.

The storm also felled a number of power lines, and authorities disconnected electricity from some of the worst-hit areas to avoid electrocutions.

Heavy rain damaged paddy crops and strong winds uprooted banana and papaya trees along the coastline, while many roads also suffered damage. Vehicles remained off the highways in most parts of Nagapattinam and Karaikal districts, the Press Trust of India news agency reported.

Speaking to reporters in a news conference in Salem, Tamil Nadu’s chief minister K Palaniswami said relief work had already begun and that the state was on a “war-like footing”, with thousands of workers on standby.

They include two naval ships deployed to the coast with divers, helicopters and inflatable boats.

He also announced that the families of the deceased will be provided Rs 100,000 (£1,085) each from a public relief fund.

Southern India’s cyclone season runs from April to December. In October, Cyclone Titli killed at least two people in Odisha state.