Complex sentence: The three men pressed on, jumping over the destroyed gun, however, one of the Indonesians was still alive and fired off a burst as the men passed, fatally wounding the Bren crew, before being killed himself by a grenade.
Split into simpler sentences: The three men pressed on, jumping over the destroyed gun. However, one of the Indonesians was still alive and fired a burst as the men passed, hitting the Bren crew, before being killed himself by a grenade.