Police have arrested an armed teacher who barricaded himself in a classroom and fired his gun, forcing the evacuation of a high school in the US state of Georgia.

Dalton Police Department spokesman Bruce Frazier said the teacher was taken into custody after a 30- to 45-minute standoff with officers Thursday morning (AEDT).

Police named the teacher involved as 53-year-old Jesse Randall Davidson, a history teacher who also served as a commentator for the Dalton High School football team.

No one was directly injured in the incident, while one student reportedly suffered an ankle injury running inside the school as the building was evacuated.

Mr Frazier told The Associated Press that Mr Davidson didn’t appear to want to hurt the students or fellow teachers, saying fired his gun at an exterior window when the principal tried to enter the classroom.

“I don’t know whether he was just firing the gun off to let people know to back off or what,” Mr Frazier said.

Police earlier tweeted that the school was evacuated and in lock down in response to the incident.

“The area inside the school has been evacuated and there are no students believed to be in the school at this time,” Mr Frazier said.

“The school is locked down. DPD and Georgia State Patrol are responding.”

Mr Davidson faces six charges, including aggravated assault involving a gun and terroristic threats and acts.

Other charges include carrying a weapon in a school safety zone and reckless conduct.

The incident occurred on the same day students returned to Florida’s Majory Stoneman Douglas High School, just two weeks after a gunman claimed the lives to 17 people shooting massacre.

The standoff and arrest also comes after President Donald Trump backed the National Rifle Associations calls for teachers to be armed in a bid to prevent school shootings.

The Dalton students were relocated to the nearby Northwest Georgia Center and parents were asked to travel to the school.

School shooting at Dalton High School!!! We okay !!! pic.twitter.com/U4UwgYGHdV

— wesley (@wesleycaceres5) February 28, 2018

Dalton student Emma Jacobs texted her mother while she hid inside a darkened classroom, her mother, Annmarie Jacobs, told AP.

Emma said in texts that her teacher had turned the lights off and told the students to sit in a corner, adding “omg she’s putting desk in front of the door”.

Police found a “threatening” note on the floor of a classroom at the Dalton High School last week authorities said, but it wasn’t clear if it was related to Thursday’s incident.

Police said the note was found on February 21 and mentioned a threat against the school the following day.

Dalton is about 145 kilometres north of the state capital Atlanta and the school’s website says it has 2,000 students.

In a lengthy series of Twitter posts last week, Mr Trump aligned his policy with the powerful NRA gun lobby, saying the arming of teachers to combat school shootings “would solve the problem instantly.”

The President said specially trained teachers with concealed weapons would be the best deterrent against a “savage sicko” with “bad intentions”.

I never said “give teachers guns” like was stated on Fake News @CNN & @NBC. What I said was to look at the possibility of giving “concealed guns to gun adept teachers with military or special training experience – only the best. 20% of teachers, a lot, would now be able to

— Donald J. Trump (@realDonaldTrump) February 22, 2018

….immediately fire back if a savage sicko came to a school with bad intentions. Highly trained teachers would also serve as a deterrent to the cowards that do this. Far more assets at much less cost than guards. A “gun free” school is a magnet for bad people. ATTACKS WOULD END!

— Donald J. Trump (@realDonaldTrump) February 22, 2018

Florida students return

The families of the teen survivors of the Marjory Stoneman Douglas High School shooting gathered to support students returning class for the first time Thursday (AEDT).

About 3000 students, many carrying white flowers, wove through hundreds of uniformed police officers to get to class.

The school district was easing them back into their routine with a half-day of classes scheduled to begin with what is normally the students’ fourth period.

That was where the students were in their day when a 19-year-old man who had been kicked out of the school is accused of beginning his rampage.

Not all of the school was reopened. The building where the 14 students and three educators were fatally shot on February 14 will remain closed, officials said, as state lawmakers contemplate tearing it down and replacing it with a memorial to the victims.

Jeannine Gittens, 44, and Janine Hills, 47, drove to Douglas ahead of the bus their sons rode in to be there for their arrival.

“We just wanted to make sure they know we are there and that they have our support,” said Ms Gittens, who said her son Jevon, a 16-year-old, and his friend had ridden the bus “to make today feel as normal as possible”.