A 30-year-old man who stopped to offer help to a motorist he thought was in difficulty was shot and critically wounded yesterday on a street in Wheaton, Montgomery County police reported.

That incident was followed by a series of events that included the abduction of an elderly Colesville couple and ended with the apprehension of a suspect at Montgomery General Hospital in Olney, where the couple had driven, ignoring their abductor's orders that they drive him to North or South Carolina. The couple was not harmed.

Police would not identify either the wounded man, who was reported in critical condition at Suburban Hospital, or the couple, saying that releasing their names might endanger them.

Late last night police were questioning the suspect, who was taken into custody about 6 p.m. at the hospital.

The series of events began about half an hour earlier, police said, when the 30-year-old man stopped his car on Bel Pre Road in Wheaton to aid a man driving a green and white van. The circumstances surrounding the shooting were unclear last night.

Police said they were first called to a shopping mall in Silver Spring where it was reported that a pedestrian had been struck. They said they found the van and learned that its driver had been hit by a car nearby and then fled on foot.

Police said the man, whom they described as middle-aged, was apparently unhurt by the accident and ran north on New Hampshire Avenue to Snider Lane in nearby Colesville, where he allegedly broke into the home of the elderly couple and ordered them to drive him in their car "to the Carolinas."

The couple instead drove to Montgomery Hospital, where officials summoned police when the man became disorderly.