A young Russian man who said he had a bomb in a brief-case fired two blasts from two sawed-off shotguns in the courtyard of the U.S. Embassy today.

There were no injuries and he was arrested by Soviet militiamen after embassy officials persuaded him to leave the grounds, according to embassy officals.

It was the second such breach of U.S. Embassy security recently. On March 28, a Soviet merchant sailor with a bomb strapped to his waist entered the building with an American. He exploded the bomb after hours of negotiations failed and Soviet police opened fire. He died later in a Soviet hospital.

Today's incident occurred at about 8 p.m. (noon EST), according to a U.S. spokesman. The man forced a taxi driver to drive him past Soviet gate guards and into the embassy inner courtyard.

He talked to an embassy telephone operator who summoned Marine guards.

An embassy spokesman refused to release the Russian's age or identity. However, other sources said he was "a young man, under 30 years old." Soviet police confiscated the briefcase.

On Tuesday, five ethnic Germans tried to enter the embassy. Four made it inside but were persuaded to leave. Yesterday, three more tried to enter but were blocked by Soviet guards at the entrance. Many ethnic Germans who have inhabited central Russia since the 18th century want to emigrate.