A 16-year-old student shot a classmate inside a Maryland high school bathroom on Friday — just days after alleged teen gunman Colt Gray shot and killed four people at his northern Georgia school.

The 16-year-old boy, during his first day at Joppatowne High School, fired a single shot in a first-floor boy’s bathroom following an altercation, striking the 15-year-old around 12:35 p.m., Harford County Sheriff Jeff Gahler told reporters at a press conference.

The school’s security officer and principal did not hear the shot, but heard the resulting commotion it sparked, the sheriff said.

Students dragged their wounded classmate into the hallway, where school nurses attended to him before he was airlifted to a hospital in serious condition.

The shooter fled to a nearby apartment complex and started banging on doors looking for a place to hide, police said. He was taken into custody “within minutes,” Gahler said. 

“It’s a tragic day, four days into the school year,” he added.

“We’re all familiar with the horrible shooting in Georgia that took four lives just a couple days ago, and here we stand in Harford County with a school shooting,” Gahler said.

The teen gunman is previously known to law enforcement, he added.

It is not clear what type of weapon he used, nor was the gun recovered, officials said.

“I don’t know whether that means he has a juvenile record. We have calls for service that have involved him in the past, I do know that,” he told reporters.

Law enforcement is not permitted to speak with the suspect per Maryland’s “criminal friendly laws,” Gahler said. But after speaking with the district attorney’s office, he believes the teen will be charged as an adult without a police interview due to “overwhelming evidence.”

Within 15 minutes of the shooting, which was initially reported as an active shooter, more than 100 law enforcement officers from various agencies swarmed the high school, located about 25 miles north of Baltimore.

Students were being evacuated by 12:45 p.m., WBAL-TV reported.

Senior Christopher Buniff told the outlet he was walking back from his third period class when he heard a loud bang behind him.

“I pulled out one of my headphones and heard was screaming and yelling and students running … I got into my class and they locked down the school for about five minutes,” he said.

Freshman Ny’jae Davis said she “was walking towards class … and I just heard a loud pop. I didn’t even know what it was and then I saw everybody running” and joined in.

“We are just devastated to be a part of this awful group of schools to have experienced things like this, and we’re going to do everything we can to make sure this absolutely never happens again,” Harford County Public Schools Superintendent Sean Bulson said.

The shooting scare comes just two days after 14-year-old Colt Gray allegedly opened fire at Apalachee High School in northern Georgia, killing two students and two teachers and wounding nine others.

Colt and his father Colin Gray, who allegedly purchased the AR-15-style rifle used in the massacre for him for Christmas — months after the boy was accused of making school shooting threats. Both have been been arrested and charged with murder.

The pair made their initial appearances in court on Friday, where they learned they could spend the rest of their lives behind bars.