A Manassas man was arrested and charged with attempted murder and robbery in two Fairfax County bank robberies yesterday, including one in which a man working on a surveillance camera was shot at when he tried to pursue a holdup man.

Robert A. Steinberg, 39, was arrested near his home by FBI agents who, working with county police, traced him through information developed from a passer-by's tip, police spokesman Dave Russell said.

The first bank robbery occurred at 9:25 a.m. at the Guaranty Bank and Trust Co. branch at 8724 Little River Tpke. when a man wearing a motorcycle helmet approached a teller, displayed a weapon and demanded money, Russell said.

After the man fled with an undisclosed amount, Russell said, Anthony Laudermilk, 18, who was changing the film of the bank's surveillance camera, learned what had happened gave chase.

"I ran behind the woods and I hollered at him and asked him to stop," said Laudermilk, who works for the Mosler Co., a Bethesda firm that supplies banks with electronic security. "He was pointing his gun at me -- I don't know if he was shooting at me or just shooting."

One shot was fired, Laudermilk said, and the holdup man then escaped in a car.

Russell said that about a half hour after the first robbery, two tellers at First American Savings and Loan, 14098 Lee Hwy., were held up by a man wearing a motorcycle helmet. The man was carrying a container of money out the door when a red-dye packet inside exploded and he dropped the money and ran, he said.

Police said they believe that the holdup man then hid in the area rather than going to his car.

Russell said Steinberg's arrest resulted from a tip from a passer-by who had seen the commotion resulting from the robbery at the Guaranty Bank and Trust office. He told police he had seen a man wearing a motorcycle helmet and acting suspiciously the day before and gave a partial description of the man's car, Russell said.

Police and FBI agents searched the parking lots at both banks, found a car matching the description at First American and were able to determine where its owner lived, Russell said.

Russell said FBI agents were waiting for Steinberg near his home, where he was arrested about 1:30 p.m. Steinberg was charged with three counts of robbery and two counts of use of a firearm in commission of a felony.

Laudermilk's boss, Ed Schwartz, praised his employe for running after the bank robber, but added: "We told him it's not part of his job description."