Kill evvery destructable in area...

[Koopa124]

I have this barrel of explosives, and once someone kills it, it explodes, and kills all the units in the region around it, but I can't figure out how to get it to kill the units around it too. Help please.

 

[Jump]

EDIT : Sorry wrong. I have to remake the trigger.

 

[Koopa124]

Thanks +rep