SEAT PLEASANT, Md. — Three people were killed and another person was injured in a serious car crash, Prince George's County police said.

Police were called shortly after 4 a.m. to Glen Willow Drive and Martin Luther King Jr. Highway in Seat Pleasant where they found an overturned vehicle in an embankment.

Authorities believe a car was traveling south on Martin Luther King Jr. Boulevard before it left the roadway, struck a sign and landed overturned in an embankment.

It's unclear what cause the driver to leave the roadway and crash, police said.

Police have not yet identified the victims.

The investigation is ongoing.