A 30-year-old teacher was charged Tuesday night with sexual assault on a student who attended Rancocas Valley Regional High School, authorities said.

Alexandra Reiner, of Eastampton, also was charged with endangering the welfare of a child. She was being detained in the Atlantic County Jail in Mays Landing and was scheduled to appear Wednesday morning in Superior Court.

Authorities said the investigation began last week when district officials contacted the Burlington County Prosecutor’s Office. Reiner, a special-education teacher, allegedly had sexual contact with a male student last month in Mount Holly and Lumberton. Authorities declined to reveal any other details.