NEW ORLEANS (AP) - Five fifth-grade students face criminal charges after authorities said four of them had sex in front of other students in an unsupervised classroom and kept a classmate posted as a lookout for teachers.

The students were arrested Tuesday at the Spearsville school in rural north Louisiana, authorities said. Two 11-year-old girls, a 12-year-old boy and a 13-year old boy were charged with obscenity, a felony. An 11-year-old boy, the alleged guard, was charged with being an accessory.

"After 44 years of doing this work, nothing shocks me anymore," said Union Parish Sheriff Bob Buckley. "But this comes pretty close."

Authorities said the incident happened March 27 at the school, which houses students from kindergarten through 12th grade. A high school teacher normally watches the fifth-grade class at the time, but went to an assembly for older students and the class was inadvertently left unattended, Buckley said.

The class, which had around 10 other students, was alone for about 15 minutes, he said.

"When no teacher showed up, the four began to have sex in the classroom with the other elementary students in the classroom with them," he said.

It took a day for authorities to find out about the incident. A student who had been in the class told a high school student about it the next day, Buckley said. The student told a teacher, and school officials notified the sheriff's office. Detectives began questioning students Thursday.

School officials did not return calls seeking comment.

The students, who were not identified because of their age, were released to their parents after their arrests, Buckley said. They will next be arraigned in juvenile court. A message seeking comment from the district attorney was not immediately returned.

Buckley said it was unclear what the children could face in penalties.