Police also said they seized drug-taking paraphernalia.
Second Army Region deputy chief Maj-General Sakda Perunavin told the press yesterday that the teens confessed to buying the weapons and ammunition from an eastern border province supplier via social media and storing them at an abandoned house. Police are trying to locate the supplier.
The teenagers reportedly told police that they sold the weapons and sent them to customers via the post, including M-79 grenades for Bt1,700, after buying them for Bt900 apiece.
After their friend was arrested on December 14, they said they moved the items to the abandoned house in a bid to avoid detection.