A witness in South Boston fired a shot Wednesday morning at a suspect who broke into a car; the suspect then allegedly pulled a knife on the witness during a foot chase, authorities said. No one was hit by the gunfire, and no arrests were reported.

The tense episode unfolded at 5:34 a.m., when Boston police were called to the area of West Sixth and F for a person breaking into a vehicle, said Sergeant Detective John Boyle, a department spokesman. While the officers were en route, Boyle said, another call came in for shots fired.

Boyle said a witness at the scene told police that he heard the sound of glass breaking and then saw a man removing a computer case from a parked vehicle. That witness came outside and chased the suspect, who fled on foot.