After three masked men held up a sandwich shop south of Dupont Circle on Wednesday evening, D.C. police made a quick arrest. A day later, the city’s police chief said they were looking for the other men, assuring residents that “we’ll get them.”

What wasn’t known until Friday, however, was that the man police arrested worked at the store he was accused of robbing. According to court records, police found him with a gun on a Southeast Washington street and later realized he was also an employee of the Pret a Manger in the 1800 block of L Street NW.

Elijah Warren, 19, of Upper Marlboro was charged with assault with intent to rob and ordered detained until a court hearing. D.C. police were searching for the other men.

Warren’s arrest came after police issued an unusual lookout for three men they said attempted an 8 p.m. holdup wearing masks and white button-down shirts with vertical burgundy stripes.

Despite the mask, according to D.C. Superior Court documents made available Friday, a store worker recognized the gunman as an employee or former employee because of his voice and build — and also because the shirts are part of the Pret A Manger uniform. It was unclear from court documents whether the other suspects are also believed to be employees.

Police Chief Cathy L. Lanier didn’t say the incident appeared to be an inside job during a Thursday news conference.

A manager at the Pret A Manger declined to be interviewed Friday. In a statement, company spokeswoman Jennifer Nelson said: “We are currently cooperating with the police as they shed further light on this case and continue their investigation. This is an isolated incident, the likes of which has never occurred at any other Pret location throughout our entire U.S. history.”

The attempted robbery occurred as the sandwich shop was closing, and it’s unclear whether any customers were inside. The court documents said all three of the men who came in were wearing the shirts and masks, and one was armed with a gun.

Police say the gunman, whom they identified was Warren, pointed the weapon at the worker and demanded money. The worker told police that “he recognized the slender build and the voice as an employee or former employee of the restaurant,” according to the court documents.

The worker told police that he tried to wrestle the gun away and that it hit his head, causing a slight skull fracture and firing one round into the air. The men then fled.

Later that night, according to court documents, members of the police department’s gun squad saw Warren on Stanton Road in Southeast, saw him grab what appeared to be gun under his shirt and questioned him. At the time, they said, he wore a black shirt and blue jeans and was not known to be a suspect in the eatery holdup.

Police said in court documents that Warren lifted his shirt slightly and then ran. During the pursuit, police said, he tossed a gun over a wall. Police found a .40-caliber weapon fully loaded with a bullet in the chamber, the gun’s hammer cocked and ready to fire, they said.

After Warren was caught, police said, he was arrested on gun charges. After later learning that he was an employee at the Pret A Manger, according to court documents, police questioned him again and Warren admitted to working there and to attempting to rob the restaurant.