According to METRO police, the red line train struck a person just before 7 p.m. on Monday at Fannin between Ross Sterling Street and John Freeman Boulevard.
Police said the person was lying on the train tracks before they were hit.
The train operator spotted the person and activated the train's emergency brake, but it did not stop in time, police said.
The red line was closed for several hours as crews investigated. Regular services were restored shortly after 4 a.m. on Tuesday.