A 15-year-old youth who admitted taking part in a shooting rampage in a Suitland pool hall last February broke down sobbing in court yesterday after he described the attack, in which the intended victim escaped but two bystanders were killed.

The youth, Darren Brodie, who was granted immunity from prosecution in return for his testimony, identified Antonio F. Gaskins, 22, as one of three gunmen who opened fire the night of Feb. 20 in Players Billiard Parlor, in what police said may have been a drug-related dispute.

Gaskins, charged with two counts of first-degree murder, faces a possible death sentence if convicted. Testimony in his trial began yesterday in Prince George's County Circuit Court.

Brodie, who gave brief, often muttered responses to most of Assistant State's Attorney Jeffrey Harding's questions, testified that he, Gaskins and a third person entered the pool hall intending to kill a man who had had a dispute over money the night before with Gaskins's brother.

As Brodie and Gaskins opened fire with pistols, and the third assailant began firing a shotgun, Brodie testified, the intended victim, who was wearing a protective vest, dived for cover beneath a pool table.

Richard Steeley, 66, a retired government worker who often sat and drank coffee in Players, was struck in the head by a bullet and killed.

Harold Worthington, 43, who had stopped at Players moments earlier to use the bathroom, also was killed.

The prosecution alleges that both rounds came from Gaskins's .38-caliber pistol. Brodie was firing a .357-caliber revolver. Gaskins has pleaded not guilty.

When asked by Harding to point out Gaskins in the courtroom, Brodie tentatively raised a finger toward the defendant.

He then clenched his hands into fists, pressed them together and began to sob and heave, prompting Judge Audrey E. Melbourne to call a recess and break early for lunch.

The alleged third assailant, Rocky Earl Bell, 17, of Suitland, has been charged as an adult with murder and is awaiting trial. He does not face the death penalty, however.