Four people have been killed after a police officer accidentally detonated a grenade during a security demonstration.

The blast from the grenade, which exploded at a university on the Indonesian island of Sulawesi, killed the police officer in question as well as three other people, according to the Jakarta Post.

Brigadier Haidir of the Southeast Sulawesi Police Mobile Brigade pulled out the pin on a grenade to show members of the university's security staff.

Moments later it exploded, killing Brigadier Haidir as well as three staff from Haluoleo University, while eight more people were injured.

The Haluleo University on the island of Sulawesi where the explosion took place

The blast reportedly occured at around 3.30pm.

One of the injured was another member of the police's bomb disposal squad, who was explaining bomb materials to the university's security officers when the grenade exploded.

Brigadier General Agung Sabar Santoso, the chief of the police force, told the Jakarta Post an investigation into the cause of the explosion was underway.