Investigation into NSW prisoner's death

The shooting death of a prisoner who was allegedly trying to escape after he was treated at Lismore Base Hospital is being investigated by NSW authorities.

Prison officers have shot and killed an inmate who was trying to escape after he was treated at a northern NSW hospital.

A NSW Police and Corrective Services NSW investigation is now under way into the circumstances surrounding the prisoner's death at Lismore Base Hospital at 7.30pm on Friday.

Corrective Services said in a statement on Saturday that the male inmate assaulted one of two officers and attempted to run away as he was being led from the hospital following treatment.

It's alleged the inmate was shot after a warning shot had been fired by one of the officers.

The inmate received immediate treatment by paramedics, but died about two hours later.

Corrective Services NSW and NSW Police are investigating the incident.

All deaths in custody are subject to a coronial inquest.