The suspects apparently took off with the Postal Service worker's master key and were later seen on surveillance video using the key to enter a Studio City apartment building and steal from mailboxes.
The robbery of the mail carrier happened Tuesday around 10:20 a.m. near 5522 Vineland Ave., according to the U.S. Postal Inspection Service. Images released showed a suspect dressed in all black pointing a gun at the mail carrier.
"We take all mail theft matters seriously and are actively investigating this case," USPS said in a statement. "As this is an ongoing investigation we cannot provide further details."
Footage of the theft at the Studio City apartment complex showed two suspects rummaging through mailboxes before leaving with a bag of stolen mail. That theft happened Wednesday afternoon, according to a timestamp on the video.
Authorities say one suspect was last seen wearing a black hooded sweatshirt, black jeans and dark sneakers. He is described as 5'11" to 6'2" tall, with a slim build and between 25-35 years old.
The second suspect wore a white face mask, gray hooded sweatshirt, dark jeans and white sneakers. No description was available of the third suspect, but investigators say they drove a black BMW during the initial robbery.
A $50,000 reward is being offered by USPS for information leading to the arrest and conviction of the suspects.