On the deadly shooting at a shopping mall in the U.S., as a community mourns its loss, authorities are trying to understand how and why this happened.

"A full day later, and we're learning a lot more now about 22-year-old Jacob Tyler Roberts. The man police say walked into the mall with a stolen semi-automatic rifle and opened fire."

Jacob Tyler Roberts

Craig Roberts, Clackamas County sheriff, said,"We haven't been able to establish how many shots were fired, but he was believed to be carrying several fully-loaded magazines."

Investigators don't believe Roberts knew his victims, 54-year-old Cindy Ann Yuille, and 45-year-old Steven Mathew Forsighth who were killed. A third, teenager Kristina Shevchenko, is in serious condition at an area hospital.

Dr. Laszlo Kiraly, surgeon, said, “She was understandably in shock given everything she had to go through I was impressed with her spirit and character."

And impressed the doctors say that she's awake and talking with her family. As officers continue to discuss how the tragic events unfolded, Sgt. Adam Phillips, Clackamas County sheriff's dept. said, “Every indication we have is he acted soley on his own in carrying out this horrible, heinous, tragic crime."

On the deadly shooting at a shopping mall in the U.S., as a community mourns its loss, authorities are trying to understand how and why this happened.

One that first responders say could have been much worse, Craig Roberts said,"It appeared the suspect's rifle did jam while he was attacking individuals in the food court."

All though Roberts was able to get the weapon working again, another factor, officers knew the crime well. They had trained for a similar situation at the mall earlier this year, and didn't wait for swat teams to show up. But instead moved in pairs, as thousands pushed to get out.

Craig Roberts said,"These four factors limited the suspects access to potential victims and gave him less time to harm others."

Still not fast enough for three families suffering tonight, or a community struggling, like investigators to understand what happened here.

Jay Gray, Portland, said," Late this afternoon we've learned investigators found and searched Roberts car in the parking lot here. They won't say what if any evidence they found inside."