Well, it wasn't light yet when the gunfire starts.
( Well ( , ( it ( ( ( ( was n't ) light ) ( yet ( when ( ( the gunfire ) starts ) ) ) ) . ) ) ) )
(ROOT (S (INTJ (UH Well)) (, ,) (NP (PRP it)) (VP (VBD was) (RB n't) (ADJP (JJ light)) (SBAR (ADVP (RB yet)) (WHADVP (WRB when)) (S (NP (DT the) (NN gunfire)) (VP (VBZ starts))))) (. .)))
When the gunfire had started, there was light.
( ( When ( ( the gunfire ) ( had started ) ) ) ( , ( there ( ( was light ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT the) (NN gunfire)) (VP (VBD had) (VP (VBN started))))) (, ,) (NP (EX there)) (VP (VBD was) (ADJP (JJ light))) (. .)))