Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

Three New Mexico teenagers accused of beating to death two men who were sleeping in a vacant lot giggled as they delivered their blows, a survivor of the vicious attack told NBC News on Monday.

"They thought it was funny," the victim, who goes by the nickname Skeets, said after he returned to the Albuquerque crime scene.

"They were giggling and laughing at us, mocking us, calling us homeless. I said, 'I don't know why you guys are bothering us. We didn't do nothing to you guys.'"

He escaped after trying to lure the masked teens away from his two friends by running — they chased him, but eventually returned to the others on the lot, beating them beyond recognition.

"They were real cowards," he said.

Alex Rios, 18, Nathaniel Carillo, 16 and Gilbert Tafoya, 15, were arrested shortly after the bodies were found and confessed — admitting they had been attacking the homeless for a year and had assaulted dozens in just the last few months, according to court papers.

"They were real cowards."

All three were ordered held on $5 million bond after a Monday afternoon arraignment. Prosecutors said they intend to charge Carillo and Tafoya as adults under the state's serious youthful offender statute.

Detectives are trying to track down other victims by reviewing unsolved homicides and talking to transients about attacks that may not have been reported, Officer Simon Drobik told NBC News.

"Because of the nature of the violence they committed on these victims, this isn't the first time they done this," Drobik said. "We believe they did commit other crimes like this."

Skeets said that he is not homeless but went to the field to drink and hang out with "Al," an older man he described as his brother or uncle. A third man he knew only as "Cowboy" and a female acquaintance were also there.

"We were just quietly sleeping and watching the night skies and they jumped on us," he said. "They cheap-shotted us."

He said he got up and fought with the attackers but could not fend them off.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

"Right when I picked up Al, they hit him with a bat, hit him right across the face. And someone hit me with a cinderblock and then they hit me with the bat," said Skeets, who had ugly bruises across his back and torso and a swollen knee.

Skeets and the woman managed to escape, but the suspects showed no mercy to the men who couldn't get away, police said.

The teens told police they used their hands, bricks, a metal fence pole and wooden sticks to bludgeon the victims.

"All three of them took turns picking cinder blocks over their heads and smashing them into the male subject's faces," according to the criminal complaint.

The suspects variously estimated the attack went on anywhere between 20 minutes and an hour.

Afterward, the 16-year-old scooped up dirt, put it on the beaten men's faces and said, "Eat mud, bitch," the youngest teen told police, the court papers say.

The assault was so brutal, the victims could not be immediately identified, said police, who were stunned by the senselessness of the crime.

"It's so much hate and they're so young," Drobik said.

Tafoya's father told NBC affiliate KOB that he was devastated by the allegations, particularly since his family had once been homeless.

"It's awful to know and understand your son could do something like that," Victor Prieto said. "It's hard, you know, as a parent. You feel like you've failed.

"He knows what he did and now he's got to pay for what he did," Prieto added.

The criminal complaint says the three boys were just getting home from a party when they "decided to go out and look for someone to beat up."

Asked what motivated the depraved behavior, the 15-year-old told cops he "was very angry over breaking up with his long-time girlfriend," the court papers say.

The 16-year-old said that afterward, they all went home and went to sleep. He said he "looked at himself in the mirror and 'saw the devil.'"

"They say the most dangerous person on the planet is a teenage boy."

Forensic psychologist N.G. Berrill said the crime may have been a twisted form of male bonding.

"They say the most dangerous person on the planet is a teenage boy," Berrill said, noting that the front lobes of their brains are under-developed while their hormones are raging.

"And if you get some boys together, they reinforce each other."

Attacking in a group also makes it easier to avoid a guilty conscience. "The more you get, the more responsibility is dispersed," Berrill said.

And while the idea of 50 or more attacks might seem unfathomable, Berrill said it's not. "The more you do, the easier it gets."

William Toyama, who lives a few doors from the crime scene, said the people who camped out on the lot sometimes boozed but were harmless.

"They would never bother anybody. They wouldn't yell at people, attack people, get in people's faces," he said.

"They just kind of try to keep to themselves back here. It was kind of the only place they had to go that was safe."

Neighbor Judith Chapelle said it was sickening that the assailants chose the most vulnerable to pick on: