(CNN) -- Three Portland, Oregon, teens are accused of luring a classmate into a shed, hitting him in the head with a crowbar, shooting him with a BB gun -- and then using a box cutter to carve a swastika into his forehead.
"There is no understanding what they did," Kelli Murrain, the victim's mother, told CNN affiliate KPTV. "Roll it around in your head and you just go, 'Oh my God.' For the grace of God I could have lost my youngest son."
The incident took place February 10, police say.
On Wednesday, authorities charged the teens with kidnapping, robbery, assault and menacing.
The suspects -- Jenna Montgomery, 15, Blue Christian Kalmbach, 15, and Jess Taylor, 17 -- have been charged as adults and were being held on nearly $3 million bail each.
A 14-year-old, also accused of taking part, will be tried as a juvenile.
According to court documents, Montgomery told police detectives that she was the "bait" to lure the 16-year-old victim, Dustyn Murrain, to the shed where the alleged assault took place.
The teens were after the victim's skateboard and cash, according to a probable cause affidavit.
All of them are students at David Douglas High School.
"I just think the whole idea is just messed up," senior Mark Collins told affiliate KATU. "Why would you do that to someone? Especially with a crowbar and BB gun."
It's not clear whether the wound on Dustyn's forehead will scar.
Kelli Murrain said her son will wear a silicon patch there to help with the healing.
"He's been severely traumatized not just physically, but emotionally," Murrain said. "It's something he's gonna live with forever, especially if the scar of (a) swastika doesn't go away. Every time he looks in the mirror he's gonna have that memory."
CNN's Mayra Cuevas contributed to this report.