(S (S (S (BASENP (DT The) (NN situation)) (VP (VBD began))) (SBAR (WHADVP (WRB when)) (S (BASENP (DT a) (NN neighbor)) (VP (VP (VBD heard) (UCP (BASENP (NN four) (NNS gunshots)) (CC and) (S (BASENP (DT a) (NN woman)) (VP (VBG screaming))))) (CC and) (VP (VBD called) (BASENP (NN 9-1-1))))))) (PERIOD .))