Chalong Police officers responded to the report at 12:33pm after being notified by the 191 emergency call centre of a shot fired in front of a house in KT Garden Home housing estate Chao Fa East Rd.
Police led by Pol Lt Col Kriangkrai Daokrajai, Deputy Chief Investigator at Chalong Police Station, together with patrol units, arrived at the scene and found a man later identified as Amonrat Thongphakdee, 19, standing nearby.
A search of the area uncovered a brown shoulder bag hidden under a cloth. Inside the bag, officers found a homemade pen gun and two rounds of 11mm ammunition.
Amonrat was taken into custody and transported to Chalong Police Station, where he was formally placed under arrest and charges were prepared.
Chalong Police Chief Pol Col Rungrit Rattanaphakdee confirmed the arrest and said investigations were ongoing to determine the motive and whether the firearm had been used.
No injuries or property damage were reported in the incident.