One suspect is in custody and another is in the hospital after a fight near Norcross High School that possibly involved a gun.

Norcross police Capt. Bill Grogan said the fight began about 10:30 a.m. Thursday in a wooded area adjacent to the school. When police got to the scene, two people involved in the fight ran, prompting a lockdown of the school.

Police believed one ran into Norcross High, and Grogan said just before 12:30 p.m. that a school resource officer took that person into custody inside the school. He was unarmed. Police, Grogan said, "have no idea" if a weapon was ever involved.

“We don’t know if there is or there isn’t,” he said. “A couple of people say that they thought that they saw a gun, but that’s all speculation at this point."

Gwinnett Schools spokeswoman Sloan Roach told Channel 2 that one of the people involved in the fight was beaten and taken to a local hospital. That person, only described as a male, was not a current Norcross High student, but may have previously attended the school, she told The Atlanta Journal-Constitution.

Worried parents descended on Norcross High during the lockdown, one of three metro Atlanta schools that were on high alert Thursday.

Alcovy High School and Liberty Middle School in Covington were put on lockdown while authorities investigated a violent threat a student allegedly posted on Facebook. A male student was being questioned in connection with the threat.

The lockdown at Norcross High was lifted after 1 p.m. Students were dismissed about 2:15 p.m., but most after-school activities were taking place as usual, Roach told The AJC.