"Officers made contact with one of the dogs and an officer-involved discharged discard occurred - that discharge was the result of a fatal shooting here in this parking lot," SFPD Public Information Officer Rueca said.
Animal Care and Control officers corralled the second dog. Police then chased after a third dog to the nearby Kimbell Playground, where officers fired, again.
"The preliminary investigation at this time, we can state non-lethal methods were used to try and detain and stop these dogs - as to which locations used non-lethal methods we haven't determined that," Officer Rueca said.
The dog that was detained at the park, and the one captured in the parking lot, are both in good condition.
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"It was really scary, it was just really scary," Fillmore resident Zubedah Shabazz said.
Animal Control officers say the dogs are Cane Corsos - a breed known for being large, strong and protective. All three were adults, weighing approximately 120 pounds each.
"We was really close nearby and we just hurried up and ran around the corner, but we did see the dogs running in the parking lot," Shabazz said.
Fillmore resident Durrell Daniels says he was bitten by a dog in a different attack here two years ago -- and lost a toe.
"What I'd like to see for it to be against the law for people to have dogs without muzzles when they come outside," Daniels said.
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The dogs involved in Friday's attack appeared to have been living in a van, but police say it is too early to confirm.
"I don't have any information of these specific dogs being in contact with police or police having interactions with the owners of these dogs, but we're working with animal control and animal control is also conducting its own investigation," Officer Rueca said.
The smaller dog that was first attacked Friday morning was taken to the vet for evaluation.
The person police saw being bitten suffered an arm injury and was taken to the hospital for treatment.
Both surviving mastiffs were in the custody of Animal Care and Control, according to police.
Bay City News contributed to this report.