A Norcross apartment fire early Sunday morning appears to be arson, Gwinnett County fire officials said.

A witness told investigators that an “incendiary device” was thrown through a first-floor window of an apartment at 6069 South Norcross-Tucker Road about 4:10 a.m.

Nobody was injured in the ensuing blaze. The fire caused extensive damage to the ground floor apartment and moderate damage to a room on the second floor.

“This intentional act could have caused serious injury or even death to the occupants who were asleep inside the apartment at the time,” Gwinnett Fire Capt. Tommy Rutledge said.

The Red Cross is helping residents of the two apartments. The fire remains under investigation.

Anyone with information is asked to contact the Gwinnett fire department at 678-518-4890 or the Georgia Arson Control Hotline at 1-800-282-5804. A reward of up to $10,000 for information leading to the arrest and conviction of the person or persons responsible for the arson is possible.