A motorcyclist struck a pedestrian Saturday in Prince George’s County in an unusual incident in which both were killed.

The accident occurred about 3:45 p.m. in the southbound lanes of Branch Avenue at its intersection with St. Barnabas Road, near an open-air shopping center south of Iverson Mall. The two major thoroughfares are in the Marlow Heights area.

There have been numerous motorcycle fatalities and pedestrian deaths in the Washington region, but few fatal crashes involving both a motorcyclist and a pedestrian have been reported.

Neither man’s identity was available. Cpl. Larry Johnson, a police spokesman, said the pedestrian appeared to be homeless.

An investigation was underway, and southbound lanes of Branch Avenue were closed, Johnson said.

No cause had been determined, but it appeared that the pedestrian was not in a crosswalk, Johnson said.