Police in California said Tuesday they may have prevented a potentially deadly incident when a teenager’s Instagram post led them to a cache of weapons and ammunition.

Four guns and more than 100 rounds of ammunition were found in the bedroom of a 15-year-old sophomore boy at San Joaquin Memorial High School on Monday, cops said. Earlier in the day, the teen, who is not being identified, had threatening rap lyrics posted to his Instagram account. When school officials were alerted, they contacted authorities.

“We have every reason to believe that he was reaching out for help,” Fresno Police Chief Jerry Dyer said. “The weapons were present. The ammunition was present. Perhaps even the mindset was present to carry out those threats.”

The Instagram post that set events in motion involved a reworked stanza of Eminem’s rap song “I’m Back.” The verse that was posted references the Columbine massacre, guns and shooting. The boy told detectives he did not post the lyrics and his computer may have been “hacked,” according to The Fresno Bee.

“The weapons were present. The ammunition was present. Perhaps even the mindset was present to carry out those threats"

- Jerry Dyer, Fresno police chief

But when police searched the boys room, they say they found an AK-47 Airsoft gun, a .357 –Magnum revolver, a 12-gauge shotgun, a .22-caliber rifle, more than 10 rounds of ammunition, a box of shotgun shells and a bulletproof vest, the LA Times reported.

Linden Lindahl, the teen’s attorney, said the Airsoft rifle had a bright orange tip that signified it was not a real weapon and disputed the location where the guns were found, according to the Fresno Bee. Lindahl said the weapons were in a basement area that could only be reached through a closet in the teen’s father’s bedroom.

The teen faces a felony charge of making terrorist threats, Dyer said. He was in police custody Tuesday at a hospital and was undergoing a mental evaluation. After his release from the hospital, the teen is set to be booked into Fresno County juvenile hall.

“His family describes him as a quiet kid with a circle of six to seven friends,” Lindahl said.

San Joaquin Memorial was closed Tuesday as a precaution, the LA Times reported. A Catholic elementary school the teen had previously attended was also closed. Both schools were open Wednesday.