A man was killed by a fallen tree in Brooklyn on Saturday, the first casualty of the nor’easter that is bearing down with extreme wind gusts on the Atlantic Coast.

A 56-year-old man suffered “trauma throughout his body” when heavy winds brought down the tree near 700 Euclid Avenue in East New York around 3:30 p.m., a police spokesman told The Post.

The unidentified man was rushed in critical condition to Brookdale Hospital where he was pronounced dead shortly after 5 p.m., cops said.

Wind gust speeds reached up to 60 mph on Saturday — and are expected to shoot up to as high as 80 mph in some areas on Sunday.

This is a developing story.