It started as a routine shoplifting arrest, one of about 3,000 a year at Woodward & Lothrop department stores here.

But Wednesday night it ended differently. A young suspect at Woodies' downtown store pulled a gun from her clothing, shot a store detective and was later shot and wounded after she kidnaped a motorist and exchanged gunfire with three D.C. police officers, according to police.

In the aftermath, both D.C. police and Woodies' security personnel said they were puzzled about how and why a usually nonviolent crime such as shoplifting ended in gunfire this time.

"This is a very, very, very unusual case," said Lewis Shealy, Woodies' director of security. In his 11 years with the store, Shealy said, Woodies' detectives have made more than 33,000 arrests, of which only three involved weapons. Wednesday's shooting marked the first time that shots were fired or a store detective was wounded, he said.

Det. Rufus Jenkins of the D.C. police robbery squad said the incident began when a third-floor store detective spotted a young woman stuffing "a multitude of dresses" into a shopping bag. The store detective radioed to other guards, Jenkins said, and when they approached the woman, she slipped into an elevator that was headed down. Guards converged on the elevator on the first floor, and in a scuffle the woman fired a pistol and hit store detective John Cooper in the leg, police said.

Running outside where she dropped her shopping bag, the suspect pulled her handgun on a motorist, jumped into the car and forced her to drive, with police chasing them at high speeds through several downtown blocks, according to police. The driver, whom police would not identify, suddenly swerved into a parking lot, stopped and fled from the car.

Police said the suspect then fired at least one shot at pursuing police and was hit several times when police returned the fire.

The suspect, identified as Anita Arlene Turner of 1218 R St. NW, was charged with armed kidnaping and armed assault on a police officer. She was in stable condition with hand and leg wounds and was being held yesterday at D.C. General Hospital's jail unit.

Cooper, the store detective, was in stable condition at George Washington University Hospital and apparently had not lost his sense of humor: "I don't think anyone likes being shot," he said, adding that when President Reagan was shot last March 30, "The president said he would rather be in Philadelphia, and now I understand what he meant."