Three men charged with the shooting deaths of Angelo Henderson, Jaison Jenkins, and Anthony Williams on Floyd Street more than five years ago were ordered held without bail at their arraignments yesterday, Suffolk County District Attorney Daniel F. Conley said.

“As prosecutors, we’re constantly trying to substantiate, corroborate, and verify the evidence,” Conley said. “One of the most effective tools in doing that is the Suffolk County Grand Jury. Boston Police and Suffolk prosecutors didn’t quit on this case five years ago and we won’t quit now.”

JEMALD “NATURAL” ALLEN (D.O.B. 8/5/78) of Roxbury; his nephew, RODERICK “RA-RA” ALLEN (D.O.B. 2/14/85) of Mattapan; and ANTWOIN “TWIX” FIELDS (D.O.B. 9/7/79) of Dorchester are each charged with three counts of murder and unlawful possession of a firearm in connection with the Sept. 4, 2004, homicides.

Assistant District Attorney John Pappas of Conley’s Homicide Unit told a Dorchester District Court judge that the defendants were at a Labor Day cookout at the Franklin Field Housing Development when a 24-year-old associate of theirs was shot in the face on Stratton Street after returning from a trip to the liquor store. That man told people at the cookout that he had been shot by assailants from Floyd Street, Pappas said.

“All three defendants were then observed leaving the party together,” Pappas said.

Meanwhile, the prosecutor told the court, Jenkins and Williams were sitting in a minivan on nearby Floyd Street as Henderson stood next to them. Moments after the first shooting, two men approached the minivan from between two houses and a third approached from the opposite direction.

“Shoot them all,” someone yelled, according to the prosecutor.

“What followed was nothing short of a massacre,” Pappas said. “There were multiple gunshots. Williams and Jenkins, sitting defenseless in the minivan, were shot numerous times and killed. As the gunfire erupted, Angelo Henderson … fled through a yard on Floyd Street and wound up on Callendar Street, where he collapsed from what turned out to be a fatal gunshot wound to his abdomen.”

There was and remains no indication that any of the victims had been involved in the prior shooting on Stratton Street, prosecutors say.

In the aftermath of the deadly violence, Pappas said, all three defendants were seen racing back toward Franklin Field. Jemald Allen was seen with a semiautomatic handgun and Fields was seen handing an object to another person, Pappas said.

Boston Police investigators recovered “a substantial amount of ballistics evidence” at the scene, including numerous 9mm shell casings. Pappas also said that some of the casings recovered on Floyd Street matched 9mm casings recovered at the scene of an earlier shooting on Blue Hill Avenue.

Jemald Allen is represented by attorney Michael Bourbeu, Roderick Allen by attorney Elliot Weinstein, and Fields by attorney Peter Parker. All three will return to court on April 8.