The second incident was captured on video outside 7Q Spa Laser & Aesthetics.
"It happened early in the morning, 5:40, and it was a Budget rental, big truck, that backed up to the parking lot. And they're like, slowly, one by one, they're dropping the packages," said Lilia Serobian, one of the owners of the spa, adding that the "huge pile" contained various sizes of packages, and all of it was US mail.
According to the report, a spa employee found the pile of boxes and envelopes in the parking lot, after which police were called to the scene. A USPS manager collected the mail.
More U.S. mail was found in an alley less than a mile away from the spa, according to police. It was not immediately clear whether both piles were dumped by the same truck.
Postal Service investigators are looking into the dumping incidents, Glendale police said.
Inspectors will try to determine which post office — and specifically what route— the mail came from, as well as who rented the truck. -KTLA
The report comes amid a national dialogue over mail-in ballots for November's election - with President Trump and his allies repeatedly claiming that the process would be tainted by corruption and cause huge delays.