After viewing surveillance video from the Westroads Mall, Omaha Police Thursday had a better understanding of what took place that led a troubled young man to shoot 13 shoppers and store employees Wednesday afternoon.

Just after 2 p.m., a sea of people emerged from the Von Maur department store. "It's a very massive crime scene," said Omaha Police Chief Thomas Warren.

What turned shoppers and employees into a shooter's victims was only starting to unravel. "It appeared to be random, certainly very spontaneous and the duration of the event last only a few minutes.”

Police have tracked the gunman's actions based on surveillance tape from inside.

Police say Robert Hawkins came inside the store and then abruptly left. "It appeared the shooting victims were randomly selected," said Chief Warren. "It didn't appear anyone was targeted."

Six minutes later, Hawkins returned, but this time he was concealing an AK-47 rifle. He headed straight to the elevator and a short trip to the third floor. "Upon exiting the elevator, he immediately started firing shots."

It is during this time police got their first call for help at 1:42 p.m., a 911 call from someone inside Westroads. Police then issued a “shots fired” call.

"There were several individuals mortally, fatally injured, several shots fired throughout this incident,” said Chief Warren.

One shot from high up in the atrium, claimed a victim below, but in one area, the shooter found a cluster of victims. "There were several people who fled immediately once shots were being fired.”

Police arrived and found eight people murdered and a shooter who had turned the gun on himself. The other two people died at the hospital.

Police say they believe the entire incident took less than six minutes. They say they had no opportunity to intervene, that by the time they arrived, the shooting was over.