An 18-year-old man was rescued Sunday by Arapahoe County area first responders after he fell roughly 30 feet down a shaft inside an abandoned missile silo near the town of Deer Trail and sustained serious injuries.

The man, who entered the silo with a group of seven teenagers, was stuck for hours in the shaft. A friend who attempted to assist him became trapped and was also rescued.

Altura Fire Chief Richard Solomon, one of two rescuers who found the teens in the silo, described the inside as “a maze of tunnels” and “twisted metal,” which made the operation “a difficult rescue.”

“When we finally did make contact, we did finally hear them yelling, and we were yelling back for them,” said Travis Daniels, the other rescuer from Altura.

Daniels, who used a body board to rescue the injured man, said he followed the screams of a teen who was trying to help his injured friend, adding the injured man couldn’t scream for himself.

Solomon said it took 30 minutes to inform rescuers outside that they found the group and the injured man.

The incident occurred at 3:30 a.m. near 82000 East County Road 22.

Upon arrival around 6:30 a.m., rescue teams were approached by five teens outside of the silo – two boys and three girls. They told first responders that a boy and the 18-year-old man were trapped inside of the silo, according to an Arapahoe County Sheriff’s Office news release.

After a two-hour rescue operation, a helicopter airlifted the man to a hospital. He is expected to survive, the sheriff’s office said.

Arapahoe County Sheriff’s Office spokesperson Ginger Delgado, who was at the scene Sunday morning, called it a “dangerous” and a first-of-its-kind “incredible rescue,” she told The Denver Gazette.

“It was remarkable,” she added.

Delgado said the teens slipped through an opening in the silo’s gate, went in about a half-mile deep, and then one of the teens fell down a shaft.

“It was pitch black,” said Delgado. “There’s no cell phone communication, and one kid got out to call 911.”

Firefighters from Sable Altura, Deer Trail, Agate and Bennett Watkins fire departments were present at the scene.

“It was a very technical, extremely dangerous rescue,” added Delgado. “The fire chiefs were telling me that they had never done a rescue like this in their entire career.”

Silo exploring is a common thing in parts of the county, said Delgado, though she added Sunday’s incident has never occurred before.

“We’ve never ever gone inside (a silo) for a rescue before,” she said, adding the teen and his friend were trapped inside of the shaft for roughly five hours.

The silo the teens entered was a shelter built in the 1960s amid fears of the Cuban Missile Crisis and the Cold War, according to reports by Denver Gazette partner 9News in 2016.

The spot is now notorious for graffiti and urban exploring. The sign in front reads “no trespassing.”

The 18-year-old man who was injured is being charged with 3rd degree criminal trespassing, while the other teenagers were released to their parents with pending charges, according to the sheriff’s office.

All of them are students in the Cherry Creek School District, sheriff’s officials said. Authorities didn’t release the names of the injured man or the teens involved.

The 18-year-old, Delgado added, is “for sure” lucky to be alive.