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"It appears that the reason why he went to the location was to shoot his wife because he was distressed over their recent marital separation," said Paul Fitzpatrick from the Simi Valley Police Department.
Simi Valley police say injuries sustained by the three other victims range from minor to critical. They've been identified as 18-year-old Christian Carpio, 41-year-old Lydia Carranza, and 37-year-old Gloria Castrellon.
Carranza's children told Eyewitness News on Thursday that she knows the shooter, and that Paredes apologized to her just before he started firing.
"Before he shot my mom, he's like, 'Lydia I'm sorry I had to do this to you,' and then he shot her," said Celina Carranza, daughter to one of the victims.
Celina Carranza says her mother was shot in the right arm and in the chest and that she's doing well after emergency surgery. She also adds that her mother and another woman made it out alive by playing dead.
"The guy kept running in and out of the room to see if they were like dead. He called the detective saying he killed everybody. My mom was telling everyone to hold their breath every time he came in so he wouldn't shoot at them again," she said.
Simi Valley police say Paredes and his wife have a 7-year-old daughter. He has no prior record, and no history of violence -- just the one that started and ended at the dental office.