《俺が威嚇射撃する ゴーを出したら 突入だ》
I will fire a warning shot, when GO begins (must) rush in.
My shot at figuring out a translation above.
I figure it's something like, I will fire the warning shot, then say go, then we proceed, which is what happens next in the show. Just now seeing how it all connects grammatically.
Edit:
《瀬文隊長が威嚇射撃後 ゴーの合図で突入します》is spoken right before they go in by another officer. From that it's clear that:
After the commanding officer fires some warning shots, on the signal "go", we storm in.