operate their weapons in self-defense. michael holmes is there. >> reporter: armed and uniformed men enter a building at a ukrainian military facility in the crimean capital. the aftermath of what appears to be the first shooting incident of this crisis. there have been standoffs at ukrainian military bases all around crimea for the past two weeks. most have been uneventful, but today at this base, gunfire erupted. an ambulance arrives amid reports of injuries while local so-called self-defense groups guard the gates outside. this man on the phone with his daughter said her husband was wounded in the incident after armed and masked men burst on to the base, breaking windows and telling staff to lay on the ground. it's not clear how or why the shooting began. pro ukrainian sources said the attackers fired first.