The three people were taken to Reston Hospital Center in Virginia after disembarking from the plane, said Jonathan Freye, a spokesman for the Metropolitan Washington Airports Authority.
A United Airlines spokeswoman said in a statement that Flight 1597 from San Juan to Washington encountered turbulence shortly before landing.
"The aircraft was met by local medical authorities and one passenger and two flight attendants were transported to an area hospital for further evaluation," said the statement from United Airlines, which provided no further details.