Complex sentence: When they reach the landfill where Tony is living, they find him and his partner dying as they were tortured by Fung and his gang just as a large group of assassins sent by Fung show up and a huge gunfight ensues.
Split into simpler sentences: When they reach the landfill where Tony is living, they find him and his partner dying as they were tortured by Fung and his gang. Soon, a large group of assassins sent by Fung show up and a gunfight ensues.