A construction worker fell and was critically injured at the construction site for the National Museum of Africa-American History and Culture on the Mall Wednesday night, authorities said.

The worker fell about 20 feet from scaffolding into an underground trench in the 1400 block of Constitution Avenue NW, said Timothy Wilson, a spokesman for D.C. fire and emergency services.

The accident happened about 7:15 p.m. The construction worker was transported to a hospital in critical condition.