In a day of several unusual automotive mishaps, one car crashed into a house in Fairfax County, and three other cars burned in separate incidents elsewhere. Four people were injured in what appeared to be the most serious of the incidents.

One of the four injured was in critical condition after a car crashed and caught fire about 1 the 3000 block of South Dakota Avenue NE, according to the D.C. fire department. The fire was relatively small, and was quickly extinguished, the department said.

Another car erupted in flames about 12:30 p.m. on 18th Street NW near M Street, just west of Connecticut Avenue. The cause of the fire was not immediately known. No injuries were reported, the fire department said.

A witness said bystanders helped a street vendor pull his cart out of harm’s way.

In the third fire incident, flames engulfed the front of a vehicle in Montgomery Village Avenue at N. Frederick Avenue, in the Gaithersburg area, the Montgomery County Fire Department said.

In the Lorton area of southeastern Fairfax County, a car crashed into a house on Lorton Station Boulevard near Pohick Road.

According to a witness, the car crossed a median and sheared at least two trees before pushing its front end partway through a siding wall.

The police said no injuries were reported. The cause “isn’t clear,” they said.