after what police believe might have been a third suspect and an executed search of a bobby trapped townhome. here is how it unfolded minute by minute. >> shots heard in the area. >> reporter: it's 10:59 a.m. in san bernardino. the first dispatch calls go out and within seconds, information starts trickling in. >> subject is still inside the business. building number three. possible active shooter. >> reporter: several units start heading to the inland regional center. >> where on the building is he closest to, south or north end? >> so far i'm getting on the ground floor, a male all black clothing with a black mask. we have victims down. >> reporter: about four minutes after the initial call, the first officer arrives quickly assessing the situation. >> now we have two suspects,