Margaret Chiarizia has faced several holdup men since she has been a clerk at the Safeway store at 4865 Mac-Arthur Blvd. NW, but until yesterday she had never seen one in a three piece tweed suit.

"He looked just like a businessman," she said, recalling the young man who held her up at gunpoint in the manager's office and escaped with an equally well-dressed accomplice who stood guard. The two collected an undetermined amount of money from the office and its safe.

"Before, it was just kids with masks and dressed in jeans," Mrs. Chiarizia said.

The two men met a third at a yellow Cadillac, parded behind the store and they sped away in the car after firing five shots at the store's assistant manager, Jim Vause, store officials said.

Vause noticed the men in the store, followed them outside, chased them through the store's parking lot and was approaching their car, whin the shots were fired, store manager Bill McCausland said.

Until yesterday's robbery, the store had not been robbed since 1972, according to Denny Cessna, a clerk at the store. The robbery was Mrs. Chiarizia's sixth.

"You become philosophical after a while," she said. "Now if it comes, it comes, and you just hope it doesn't," she said. She has worked at the store 18 years.

A branch of the American Security Band, located across MacArthur Boulevard from the Safeway was robbed Friday by a well-dressed man who drove away in a silver Jaguar, police said.

The man was neatly dressed in a dark blue suit said bank manager Sheila Copeland, who declined to give further details of the holdup.

The man fired two shots inside the bank during the mid-afternoon robbery, but no one was injured, police said.

Police do not know if the two holdups were related. There have been no arrests in either case police said.

The two businesses are located in the mostly residental Potomac Palisades neighborhood, where the streets are quiet, the houses expensive and the residents wealthy.