John Marsh is with the State Bureau of Firearms. He took ABC7 along as officers knocked on doors around the Bay Area looking for guns. In June, the bureau contacted 1,011 people who are not allowed to have weapons. The operation netted more than 1,209 guns.
The sweep was ordered by Attorney General Kamala Harris.
"We have seen in our recent history some high-profile cases involving individuals who are mentally unstable who have guns who commit very heinous, dangerous, lethal acts," Harris said.
Police knew where to look for the guns because of a list created in 2007 called the Armed and Prohibited Persons System (APPS). The list matches people who have bought guns legally with court records.
State law requires people who have been convicted of felonies and certain misdemeanors, have a restraining order or are mentally ill to surrender any weapons they own, but in many cases they do not.
Mentally ill people make up 20-30 percent of the APPS list. The rest are people like one Hayward man on the list because of a history of domestic violence and a restraining order.
"We have revolvers, semi automatic handguns, rifles, assault weapons, a disassembled AK-47 and at least 4,000 rounds of ammunition," Marsh said.
According to the Department of Justice, there are 17,921 on the list statewide. Records obtained by ABC7 found 2,671 people on the list in the Bay Area with 5,666 guns.
Antioch had the largest number of APPS offenders in a single zip code at 59. The Antioch Police Department did not subscribe until ABC7 called and asked them about the list.
Other police departments know about the APPS list but are not doing anything with it because they say they do not have enough officers.
In the Bay Area, San Jose has the most people on its list -- 264 with 628 guns -- but has done little with it.
Both San Francisco and Oakland have lower numbers (134 and 233, respectively) because they enforce the list.
In February, San Jose police told ABC7 that they used the list only as a reference tool. Now they are preparing to go door to door.
"We are going to give that list to our special operations people and they are going to go through the list and then start chipping away at it, making contact with these folks," police spokesperson Jeff Smith said.
Harris wants more departments to do the same.
"What we need to do is give them dedicated resources to deal with the people on this list which is proactive work it is prevention work but it is not necessarily funded," she said.
To fill the funding gap the attorney general is backing a senate bill that would allocate money collected from gun dealers to be used for the enforcement of the APPS list.
Written and produced by Ken Miguel