A construction worker was severely injured in Midtown Saturday afternoon when a chunk of concrete fell on his head.

The worker was on the 20th floor of 317 Madison Avenue near East 42nd Street, a building currently being demolished, when the heavy block struck him, according to a fire department spokesman.

Firefighters lowered the worker to the ground, and EMS rushed him to Bellevue Hospital, where he is in critical condition with a severe head injury.