The verb "utter" can be both transitive and intransitive:
1. He didn't utter a word. (transitive, direct object = "a word")
2. "Just leave me alone", he uttered loudly. (intransitive, no object)
In 1. "utter" is being used transitively; it has the noun phrase "a word" as direct object. But in 2. there is no direct object; "loudly" is an adverb, so "utter" is being used intransitively here.