a sunny day in el cajon, california, just outside san diego. 23-year-old freelance cameraman greg torkildsen is listening to his police camera. >> something happens. you know, a shooting, car crash, a house fire, something like that, i respond to it and i try to get the good shots. >> shortly after 5:00 p.m., greg hears about a man brandishing a gun inside a residential home. that man is 32-year-old kevin collier, despondent since his wife filed for divorce five days earlier. he had moved out, but now came back with a gun. when he discovers alissa is out, he instead shoots and kills their 14-month-old daughter riley and his mother-in-law. >> i had no reason not to be home. i should have been there. he thought i was going to be there. >> collier is now holed up in the house. el cajon police have taken up position outside when greg arrives.