Authorities in South Jersey have issued subpoenas to Facebook as they investigate menacing threats made earlier this week over the social networking site to students attending a Gloucester County high school.

The postings - made by someone calling himself David Prezet - were reported on Tuesday to police in Harrison Township.

According to students at Clearview Regional High School in Mullica Hill, "Prezet" threatened to "blast everyone in the school."

Students said yesterday they were on edge because the poster indicated he was coming to the school that day.

Superintendent John Horchak III said the poster claimed he was going to enroll that day. That did not happen. There is no student at the Mullica Hill school by that name, the superintendent said.

The postings, made on several Facebook accounts, have been deleted. Gloucester County Prosecutor Sean Dalton said the threats were unfounded but a high-tech crimes unit will determine their origin, said spokesman Bernie Weisenfield.

Weisenfield said he could not elaborate on the content of the postings due to the ongoing investigation.

Dennis Chambers, an 11th grader, said students, including himself, began getting "friend" requests from a David Prezet about a week ago. In an interview yesterday, he said the person then started posting inappropriate comments about girls and their pictures. Some girls "called him a creep," Chambers said, and the poster started making threats about sexual assault and other violence.

According to authorities, "Prezet" had access to students' personal information through their Facebook accounts and threatened other family members. In at least one instance, he threatened injury to one of their grandmothers.

Chambers said the person indicated that he was going to come from Ohio on Thursday and intimated that he would carry out some of the threats outside the school.

When students arrived at school yesterday, police were present.

"We were all a little antsy because we wanted to find out who the person was," Chambers said.

School officials did not offer details, though Horchak issued a statement this morning.

"I believe that it's important for the entire school community to know that there was not any direct threat to Clearview," said Horchak.

The superintendent said investigators were determined to find who was responsible for the "inappropriate postings, which created a false public alarm."

Officials at Clearview issued a statement on the school website which mentioned "misinformation that was swirling around the technology world's grapevine."

They offered no specifics.

The incident could serve as a lesson to all users of social networking Internet sites, said Harrison Twp. Chief Frank Rodgers.

"You should never tell your whole life story. Know who you're 'friending,' and don't give people you don't know personal information," Rodgers said. "Use some common sense."

"If there's a question whether it's too personal," he said, "don't post it."

Contact staff writer Sam Wood at 215-854-2796 or samwood@phillynews.com.