A heavily armed man was found dead at a Colorado amusement park

(CNN) — A man armed with guns and explosive devices was found dead of an apparent self-inflicted gunshot wound at a Colorado amusement park, potentially averting “an attack of devastating proportions,” officials said.

The 20-year-old’s body was found in a women’s bathroom Saturday morning before the scheduled opening time of the Glenwood Caverns Adventure Park in Glenwood Springs, the Garfield County Sheriff’s Office said. It appears he entered the park illegally after it had last closed.

Multiple weapons

He was “armed with a semi-automatic rifle and semi-automatic handgun and multiple, loaded magazines for both weapons,” the sheriff’s office said in a statement. “He was wearing body armor and what appeared to be a ballistic helmet. Additionally multiple improvised explosive devices, (IEDs), were discovered with the suspect and in a vehicle associated with the suspect.”

“We are, to say the least, extremely lucky that he did not fulfill whatever plan he may have intentioned,” Garfield County Sheriff Lou Vallario said during a news conference Monday. “It could have caused a devastating impact on this community, potential for many, many people to be killed and injured.”

The discovery of the man – identified as Diego Barajas Medina of Carbondale, Colorado, by the Garfield County Coroner’s Office – came three days after a shooting rampage in Maine that left 18 people dead became the deadliest of more than 580 mass shootings this year in the United States.

A note on the wall of the bathroom where Medina was found read, “I am not a killer. I just wanted to get into the caves,” Vallario said, noting investigators aren’t certain it’s tied to Medina, though there’s “reasonable suspicion” it is.

What the investigation has discovered

“The scene investigation and the forensic autopsy suggest that the decedent died by suicide and the coroner’s office is investigating the manner of death as a suicide,” the coroner’s office said in a statement.

Medina lived with his mother and brother, and investigators have been talking with them and searching the home to learn more about a possible motive, authorities said.

“We don’t see any history, we don’t see any reason, we don’t see any motive. He was just completely under the radar, Vallario said. “To the best of my knowledge at this point … there was nothing to indicate any type of warning, or any type of concern on the part of family, friends, school, what have you.”

At least two weapons Medina had were ghost guns, Vallario said. Ghost guns are kits that a user can buy online to assemble a fully functional firearm. They have no serial numbers, do not require background checks and provide no transfer records for easy traceability.

Investigators also found a “very well-put-together” fake IED in Medina’s car, in addition to a real explosive device, Vallario said. Patches affiliated with law enforcement groups were found, the sheriff said, but investigators don’t know how Medina got them.

“A tremendous amount of damage”

With the volume of weapons, ammunition and explosive devices Medina had, he “could have done a tremendous amount of damage,” the sheriff said.

Glenwood Caverns, about 160 miles west of Denver, is on atop a mountain and only accessible via a five-minute ride in a gondola.

“If he had (gone) through with … the worst-case scenario, it could have been devastating for no other reason (than) just trying to get aid and help and the number of first responders up there, let alone get victims down the mountain,” Vallario said.”

The park has been closed since Medina’s body was found.