A D.C. police officer, his gun drawn, arrived at the scene of a liquor-store holdup last night to find the robber dragging the store owner out the door as a human shield, while leveling his own chrome-plated .38-caliber revolver at the officer.

"Drop your gun or I'll blow you away," the robber shouted to the approaching officer. The merchant added his own plea. "Don't shoot," he cried to the officer. "Don't shoot."

While Officer John E. Spiegel stood in the parking lot of Montana Liquors, holding his fire, the robber pulled the trigger of his revolver. It misfired.

The robber pulled the trigger once more, and again his gun misfired, before another officer arrived and the robber finally threw down his gun and surrendered, police said, ending the tense 10 p.m. showdown outside the store at 1805 Montana Ave. NE.

The episode had begun a few minutes earlier when two men entered the store and took money at gunpoint from the cash register as well as from owner Horace Mosby and a store employe.

While the robbery was under way, a would-be customer began to enter the store, but saw what was happening and left to summon police.

Possibly concerned that police might reach the store before he could escape, the robber with the gun turned to Mosby before leaving. "You're going to escort me outside," he said.

When Officer Spiegel arrived at the store, in the Brentwood section just north of New York Avenue, he said, "this guy (the robber) was just coming out the door with (Mosby),"

". . . When you're in a position like that," Spiegel, a 10-year police veteran, recalled later, "you can't do anything." There was no place to duck for cover. He said he could only wonder: "Is he going to shoot me?"

When Sgt. Harold Titus arrived, police said, the robber could not shield himself from both officers and gave up. They said they arrested John Banks, 26, of 1537 A St. SE and charged him with armed robbery. The other suspect escaped.