(CNN) -- A gunman who opened fire at a Georgia elementary school Tuesday was armed with an AK-47 "and a number of other weapons," police said.
"He started to fire from inside the school at our officers," DeKalb County Police Chief Cedric Alexander told reporters.
The shooter barricaded himself in the school's front office with employees before eventually surrendering to police, Alexander said.
He fired approximately six shots, and police returned fire, Alexander said. Authorities said no one was injured.
The suspect is approximately 19 years old and has been detained, Alexander said. It is unclear whether he had any connection with the school.
Students from Ronald E. McNair Discovery Learning Academy, about seven miles east of downtown Atlanta, were being returned to their parents at a nearby shopping center Tuesday afternoon. The children smiled and waved and parents cheered as each school bus arrived with students aboard.
"Everybody's safe," DeKalb County Schools Superintendent Michael Thurmond said.
"This thing came out for the best," said Dale Holmes, DeKalb County's assistant police chief. "Thank God no one was hurt -- not even the suspect."
Teachers and administrators guided the students out to a lawn outside the school's gym, where they remained while investigators combed the school to make sure no other threat remained. Yellow crime scene tape marked part of a parking lot and a wall of the school.