A 71-year-old man died Friday afternoon in the Columbia area of Howard County in a single-car crash, the county police said.

They said Mark Richmond of Ellicott City was driving north on Route 29 about 1 p.m. when his car left the road and struck a barrier. He was taken to a hospital where he died, police said.

Police said they did not know why his car swerved off the road, but said they think he might have suffered a medical emergency. The matter is under investigation, they said.