Katt Williams -- Detained in Gun Investigation

4:55AM PT: Katt was just released without any charges. We're told the gun was unregistered and police are trying to find out who owns it.

Katt tells us it was all just a misunderstanding.

Katt Williams was hauled in by LAPD early this morning for a possible gun violation at a Hollywood nightclub.

Law enforcement sources tell us police got a call around 1AM that someone was brandishing a gun outside Supperclub ... and when officers arrived on scene a witness identified Katt as the suspect.

We're told police did not find a gun on Katt, but when they found one in his car -- Katt and two other members of his entourage were taken into custody for questioning.

Police have since released one of the men, and booked another on an unrelated traffic warrant.