I'm dealing with a case as a Bucks County criminal lawyer where the government is trying to include a statement from an individual who is otherwise unavailable. Normally, this would be hearsay, an out of court statement admitted for the truth of the matter asserted.
Courts have ruled that the res gestae exception to the hearsay exclusion has been said to be a dangerous rule which ought not be extended beyond the limits of reasonably immediate spontaneous declarations made in connection with a startling event by one laboring under the stress of nervous excitement caused by it. Res gestae is a generic term encompassing four discrete exceptions to the hearsay rule: (1) declarations as to present bodily conditions; (2) declarations of present mental states and emotions; (3) excited utterances; and (4) declarations of present sense impressions.
To come within the excited utterance exception, a statement must be a spontaneous declaration by a person whose mind has been suddenly made subject to an overpowering emotion caused by some unexpected and shocking occurrence, which that person had just participated in or closely witnessed, and made in reference to some phase of that occurrence which he perceived, and this declaration must be made so near the occurrence in both time and place as to exclude the likelihood of its having emanated in whole or in part from his reflective faculties.
The way I view this exception, an "excited utterance" must be so close in time to an event that there is absolutely no opportunity for a person to do anything but utter the truth. For example, if someone stands up in a movie theater and a patron yells "He's got a gun!", there's an almost uncontroverted chance that the person has a gun. Another example -- If someone yelled "He [Jack Ruby] shot Oswald" immediately after the shooting, that would normally be an excited utterance that would be admissible.