An English teacher was caught by her students snorting lines of what police believe was a cocktail of cocaine and heroin.

Samantha Cox, 24, was arrested after children at her Indiana school filmed her sat in a corner of her classroom cutting up lines of drugs and snorting them.

Pupil Will Rogers recorded the incident, which appeared to show Cox cutting up a white, powdery substance on a binder before leaning over it.

"She's in the corner, hiding with a chair and a book and what appears to be cocaine, putting it into lines," he says in the footage.

"I actually watched the footage again and again, and I just realised that my English teacher just did cocaine," he then told WGN.

The video soon spread across campus leading to Cox's arrest on suspicion of possession of a controlled substance and drug paraphernalia.

Another student told the US radio station: "You're told as a child to listen to them, respect them and stuff like that...But it's kinda hard to respect somebody who does cocaine in a classroom."

A police statement said information of Cox's behaviour was brought to their attention by school administrators after "student witnesses" informed them.

"School officials and police want to recognise and praise the student witness that brought this information to the principal very quickly," the police statement read. "Their actions showed a tremendous amount of fortitude and integrity."