The story does not actually say that the shooters heard the woman yell for help.  We also do not know how far the bullets traveled.  There is much we do not know and it is difficult to judge the seriousness of the shooters transgression without knowing more.  Presumably the DA and others involved in the criminal justice system charged the shooters as seriously as they could under the law or perhaps the final charges were the result of a plea bargain.  We simply do not know.