A 34-year-old Silver Spring man described to a federal court today how he was arrested and a companion was shot and killed by Prince George's County police in what the man contends was a phony robbery of a 7-Eleven store set up by police in 1967.

"We went out the door after taking the money at gunpoint , and all of a sudden, all hell broke loose," said David E. Wedler, then 19. ". . . There was shooting and shooting and shooting and shooting."

Police with shotguns were everywhere, Wedler said. "I ran . . . and fell face down on the ground . . . . I seen Bill William C. Harris on his knees with his back arched . . . . Then he fell on his face."

Wedler said, "I took off my stocking mask and wrapped my pistol in it and threw it away." Moments later, he said, he heard an officer ram a shell into the chamber of a shotgun. The officer "came up to me and kicked me in the ribs and said, 'Okay, we got one here,'" Wedler said.

Thus ended the fifth and last incident in which three members of a so-called police "death squad" are accused in a $9 million civil rights trial here of staging robberies and burglaries for waiting police to ensnare unsuspecting participants.

In the 7-Eleven incident, Harris, 25, died of shotgun wounds, Wedler was arrested and imprisoned for two years and an informant who lured them into the holdup, Sydney Hartman, was never prosecuted, according to plaintiffs in the trial.

All told, two persons were shot and killed, one wounded and seven arrested in the five incidents between June and November 1967. Plaintiffs contend that police improperly directed informants to recruit participants for the holdups and burglaries in violation of the 14th Amendment right to due process.

Police deny the allegations, contending that the informants came to them with information about planned holdups and burglaries, and detectives then routinely staked out the targeted stores. Further, they say police fired on the suspects only after their orders to halt were ignored and the suspects fired on them first.

Police defendants, including the present number two man on the county police force, Lt. Col. Joseph D. Vasco Jr., are expected to testify later in the civil trial, giving their version of the incidents.