California has tough gun laws. Bad guys should never get guns, according to those laws.
A 28 year old shooter who did about 5 years in the U.S. Marine Corps bought a legal Glock 45 caliber weapon and killed 12 people before killing himself.
For the first 3 minutes of the shooting, he was the only gun in the house. The first police officer who arrived was shot several times and later died. The shooting ended when the bad guy shot himself.
Those gun laws really work.