A North Carolina mother is blasting law enforcement officers for their violent treatment of her son outside an emergency room during a mental health crisis. The teen is expected in court today facing four charges from the incident, including felony malicious conduct.

In surveillance video of the scene, which happened in December in Lincolnton, outside Charlotte, security guards are seen tackling the teenager. At another point, a sheriff's deputy punches him in the head while he's handcuffed, reports correspondent Don Dahler.

His mother, Jessica Long, told CBS' Charlotte affiliate WBTV that security officers and law enforcement escalated the situation instead of helping her son, who's been treated for mental illness in the past. "They did the worst; they made it worse," Long said.

The shocking video shows the moments Long's 16-year-old son, Hayden, was tackled to the ground and punched twice in the head. "They just immediately went for full-blown physical force," said Long. "And these were big guys, and my son's, what, maybe 120 pounds."

Long said she brought Hayden to the emergency room in December for a possible mental health emergency. She asked for a hospital security guard to help get him in the building.

"I motioned for the first guard to come out, and when he did I immediately told him that my son needed treatment," she said.

But the guard ends up grabbing him. Surveillance video shows Hayden was shoved twice – hard enough that the teen came out of his shoes.

© Provided by CBS News Sixteen-year-old Hayden Long is pushed to the ground by a hospital security guard outside the emergency room entrance.

"I jumped in the middle," said his mother, "because the guard was getting ready to tase him, and I was telling him, 'No, don't tase him!'"

When Long's back was turned, a second security officer appears to tackle Hayden to the ground. The boy stayed there for more than five minutes with both guards on top of him.

Body cam footage shows the guards tased the boy twice.

Four deputies with the Lincoln County Sheriff's Office then showed up. The boy, handcuffed and with a mouth full of blood, spit at Deputy Justin Polson.

Video then shows the deputy punching the boy in the head twice.

© Provided by CBS News Surveillance video shows a handcuffed Hayden Long being punched in the head by a police officer at the entrance of Atrium Health in Lincolnton, N.C.

A spokesman for Lincoln County Sheriff Bill Beam confirmed Polson no longer worked with the force. But just last week, Beam defended Polson's actions.

"Spitting blood in a law enforcement officer's face is a felonious assault," said Sheriff Beam, "and he had a right to stop that assault from occurring."

Officials with the hospital, Atrium Health, also say their officers acted appropriately with Hayden. "He kept saying to the officers that he had a gun and he wanted to shoot people," said Maureen Swick, Senior Vice President, System Nurse Executive at Atrium Health. "So, he took the action that he thought was necessary to contain the situation."

Long said she won't turn to Atrium for help in the future.

"No one is being held accountable except for the 16-year-old who was at the hospital for help," she said, "and the trained adults – who should have been able to handle the situation and help – made the whole thing entirely worse."

Long said Hayden was not seriously injured but is traumatized by the incident. Her attorney said Hayden spent eight days in juvenile detention, and that his family is hoping to get the charges dropped at a preliminary hearing this afternoon.