A strong explosion was felt on Saturday evening in central Gaza.
Six people died and three were injured as a result of the explosion, Gaza's Health Ministry said.
The victims were transferred to a local hospital.
Unofficial reports say the injured are members of Hamas' Izz ad-Din al-Qassam Brigade.
Israeli officials estimate that the explosion was the result of a work accident, and that those injured were attempting to take apart an old missile, possibly from 2014's Operation Protective Edge.