All I could find was this..
http://www.vpc.org/studies/wgun970228.htm Where'd They Get Their Guns?
An Analysis of the Firearms Used in High-Profile Shootings, 1963 to 2001
Date: February 28, 1997
Location: North Hollywood, California
Alleged Shooters: Emil Dechebal Matasareanu and Larry Eugene Phillips, Jr.
People Killed: Two (shooters killed by police)
People Injured: 16
Firearm(s): Multiple fully automatic assault rifles including an AK-47 type
Circumstances
On February 28, 1997, Matasareanu and Phillips tried to rob a Bank of America branch office in North Hollywood, California. While trying to escape, the two men engaged in a shootout with police. Though vastly outnumbered, the two men—armed with automatic weapons and wearing body armor—successfully held off law enforcement personnel for hours before being shot and killed by police.
How Firearm(s) Acquired
The weapons were originally bought at a gun show and then illegally resold to Matasareanu and Phillips.
I will keep looking on how they got them to auto. No info on that here. Don't know how reliable the site I got this info from was..
That stupid movie said an "AK" was confiscated from them at a traffic stop and then ordered to be given back to pay court costs. I have to assume this was before an illegal full auto conversion was performed on the gun.