Mystery surrounds nailgun attack at Sydney Buddhist temple

Mystery still surrounds a bizarre incident that left a monk and a buddhist temple president with nails in their heads at a Sydney temple.

And with one of the only two witnesses in an induced coma, the details of exactly what happened at the Vat Ketanak Khmer Kampuchea Krom temple may not be clear for some time.

Buddist monk Karuna Kim, 29, and temple president Tha Lam, 59, were both hospitalised after being hit with a nail gun on Wednesday.

Police believe one man shot the other in the head and then shot himself but investigators don't know who was wielding the weapon.

Mr Kim, who is in an induced coma, and Mr Lam were the only two in the area when the nail gun was fired.

Mr Lam's condition has improved and remains stable.