ORANGE PARK, Fla. -- A search of Fleming Island High School on Friday turned up no weapons, but MySpace posting that prompted the search landed a 16-year-old student in jail, according to the Clay County Sheriff's Office.

The posting, which has since been removed from the site, threatened to "... shoot up the school and bring a bomb to school."

"It got passed around real quickly on 'MySpace' last evening, and by this morning ... it was spread throughout the county," Clay County Sheriff's Office Detective Cory Rosepiler said.

As word spread about the threat spread, and school officials said at least 50 parents either kept the children home or pulled their child out early Friday -- including the parents of the boy accused of making the threat.

When detectives questioned the teen, he told them he did it as a joke.

"He thought that he was just sending it back and forth to his friends," Rosepiler said.

Investigators said they found nothing suspicious in either the boy's locker or his room at home.

The boy, who WJXT is not naming because of his age, was arrested and charged with "written threat to cause great bodily harm," a second-degree felony. The school expelled the student for 10 days, and administrators are recommending he be expelled permanently.

Officials also said this threat has no connection with an arson at Fleming Island High which caused the school to be evacuated on Monday.

Deputies investigating the incident said paper towels were ignited and the sprinkler system flooded portions of the first and second floors, causing thousands of dollars in damage to the facility and equipment.

A 17-year-old Orange Park boy -- and 11th grade student at the school -- was arrested Thursday night and charged with arson to an occupied school, a first-degree felony.

"They should be accountable, and they are going to be held accountable -- both by the sheriff's office and by the school board," Clay County schools spokeswoman Darlene Mahla told Channel 4's Jennifer Bauer.