They have been criminally charged and suspended from school and could face further disciplinary action as police and district investigations continue.
"The school has a zero tolerance on inappropriate behavior, and we support their position on that," Middletown Police Chief Frank McKenna said.
McKenna said he hadn't seen the tape but understood that the sexual activity - in an empty classroom after school - was consensual. He said the teens kept their clothes on throughout their exploits.
But students who saw the video reported that the boy and girl starring in it had sex on a couch with their pants down.
The three were charged with misdemeanor charges of open lewdness, indecent exposure, disorderly conduct, and possessing obscene and sexual materials and performance, McKenna said.
Police and school officials said such activity is unusual in the 9,500-student district, which covers Hulmeville, Langhorne, Langhorne Manor, Lower Southampton, Middletown and Penndel.
Truancy typically is the only trouble Neshaminy students have gotten into, the police chief said.
"This is a first for me," said McKenna, a 44-year police veteran. "It's not normal for this high school, and it's not normal for any high school, I would hope."
Edward Stack, Neshaminy school board president, called the case "unprecedented."
Stack said he also had not seen the video and probably wouldn't in case any litigation arises.
"I was very surprised and disappointed that kids can put themselves in such a position, not realizing the consequences of their actions," said Stack, a father of three Neshaminy students.
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