DeLAND, Fla. -- A father's alleged joke that went awry led to the arrest of his son on Wednesday on a charge of aggravated assault with a firearm on a law enforcement officer, according to Volusia County sheriff's officials.

Troy Williams, 22, of DeLand, was booked into the Volusia County Branch Jail in Daytona Beach on $5,000 bond after confronting a plainclothes sheriff's deputy with a loaded assault-style rifle, according to a sheriff's report.

Officials said the plainclothes investigator with the Volusia County Sheriff's Office was on surveillance Wednesday afternoon along a private road near DeLand, searching for a culprit in a stolen vehicle case.

A car pulled up to the deputy's parked pickup and a man, identified as Williams' father, asked if he needed help, the report stated. The investigator identified himself as a deputy, showed the man his badge and told him he was working on a stolen vehicle case, according to the report.

Williams' father, who later said he misunderstood what the deputy told him, went home and told his son that a real estate agent was parked down the street waiting for a customer and that someone should tell him that he's trespassing on private property, sheriff's deputies said. The father later told deputies that he meant the comment about the trespass warning as a joke.

Williams confronted the investigator about 10 minutes later, telling the deputy that he was trespassing, the report said. The deputy showed Williams his badge and told him to put the rifle down, according to the Volusia County sheriff's report. Williams asked how he could be sure the badge was real and walked to the back of the deputy's truck and loaded the rifle, the report stated.

The deputy radioed for backup, and Williams was arrested when another deputy arrived, according to the report.

The Volusia County Sheriff's Office said residents should call law enforcement if they see someone who appears suspicious instead of confronting the person.

Watch Local 6 News for more on this story.