Does the exclusionary rule apply when a police officer fails to make an announcement at the scene of an armed robbery?

Also apposite is People v. Dumas, supra, 9 Cal.3d 871, 879, 109 Cal.Rptr. 304, 310, 512 P.2d 1208, 1214. There the court said: '(T)he police had reliable information that defendant not only possessed weapons but habitually answered the door armed with a firearm. They could reasonably infer from this activity that a substantial possibility existed he would employ deadly force in order to prevent his apprehension. As the officers approached the location to be searched, they became aware of no further circumstances that would defeat this inference. They could therefore reasonably conclude at the time of entry that they were faced with an emergency and that compliance with the announcement requirements would substantially increase their peril. On these facts we hold that the officers' failure to comply with section 1531 does not give rise to an application of the exclusionary rule.'