A teenage girl on a sidewalk was one of three people killed Friday in Washington-area traffic incidents. Based on police accounts, all three appeared to be the random victims of frightening circumstances.

The girl was walking along Muncaster Mill Road in Montgomery County about 3 p.m. when two cars collided and at least one of them struck her, said Capt. Jim Daly, the county police spokesman. He said a second girl was critically injured.

Speed appeared to be a factor, police said. The incident remained under investigation.

About 11 a.m., a car ran off Interstate 95 in Prince William County. Virginia state police said it struck a barrier, flew into the air and fell onto a car driven by Matthew Wilkerson, 37, of Fredericksburg. Wilkerson was killed, police said.

In the third incident, Arlington police said, Saqlain Chowdhury, 24, of Alexandria, was fatally injured at Lee Highway and Fort Myer Drive in Rosslyn about 2 a.m. when his car was struck by another vehicle. Police said Aman Singh Lail, 24, of Baltimore, was charged with driving under the influence — aggravated involuntary manslaughter.