A man with a knife entered a woman's car in downtown Washington last night, took the wheel when she jumped out, then crashed into three other vehicles before a truck driver chased the man on foot and seized him.

The incident began shortly before 7 p.m. at 12th and K streets NW, and ended near 15th and K, where the woman's car struck an auto, knocked a tractor trailer onto a traffic island and rammed head-on into a taxi.

No injuries were reported.

Police said a woman they declined to identify was in a car with a small boy when a man with a knife suddenly tried to enter. Police said the woman sped west on K Street with the man clinging to the vehicle. At 13th Street, he got in and stepped on the foot brake. The car stopped and the woman jumped out. Then realizing the child was still in the car she appealed for help to bystanders who were unable to reach the car before it sped off.

After about two blocks, it struck a private auto, then a tractor trailer driven by Frank Fisher, 32, of Detroit, a sound engineer bringing equipment for a performance at Constitution Hall.

Finally, the car turned into 15th Street and ran into a cab driven by Marion Gray of Hyattsville. Then, according to police, the man jumped from the car and ran.

Fisher jumped from the cab of his tractor trailer, chased a man and tackled him on K Street.

Police said they arrested Royace McCain, 25, of 1221 Massachusetts Ave. NW and charged him with kidnaping. A motive in the incident could not be learned immediately.