A planned mass shooting at a Lubbock, TX, hotel was averted when a gunman's grandmother convinced him he needed to go to a hospital, according to federal authorities.

Authorities found an AK-47 in the suspect's hotel room, 17 magazines loaded with 7.62 ammunition, a black trench coat, multiple knives, black tactical pants, black tactical gloves with the fingers cut off, and a black T-shirt that said, "Let 'Em Come."

William Patrick Williams, 19, of Lubbock, was arrested Thursday and charged on Friday with making false statements to a federally licensed firearms dealer, reportedly providing an old address, according to the Star-Telegram. If convicted, he faces a maximum of five years in federal prison.

"This was a tragedy averted," said U.S. Attorney for the Northern District of Texas Erin Nealy Cox in a Friday news release. "I want to praise the defendant's grandmother, who saved lives by interrupting this plot as well as Lubbock police officers and federal agents who investigated his unlawful acquisition of a deadly weapon."