Thanet Extra reports that armed police were called after a man reported being shot at by a sniper from a house in Margate on Monday night.
The passer-by said he was fired at from a home in Millmead Road as he walked through the Millmead housing estate at about 7.30pm.
Officers in flak jackets assessed the seriousness of the situation and made what a spokesman described as "an armed inquiry" before arresting an 18-year-old man at a house.
He was cautioned for possessing a firearm with intent to cause fear of violence. A paintball firing air weapon was seized at the scene. No-one was injured in the incident.
A police spokesman said: "Some of the ball-bearing and paintball guns are extremely realistic in appearance.
"When armed officers are called to investigate a firearms incident their first duty is public safety and they will react according to what they see.
"There is always potential risk for someone using a lifelike weapon in a threatening manner to be at risk of being shot or even killed."