You cant read too much in to what a television reporter says. You could if you wanted to, infer that...
The reporter has spoken with the police prior to filming his report.
The shots were loud enough to be heard (no silencer)
The police either believe or know it is a suicide
Somebody / police heard shot/s during the incident
Or it could simply be the way that the reporter has worded his report, making assumptions that the shots were loud enough to reverberate over distance and simply regurgitating the then official line, that it was Sheila who had carried out the killings and turned the gun on her self.