Around 4:10 p.m., an anonymous caller told police that a man was beating his girlfriend in a house in the 5000 block of Bridle Way and had threatened to shoot the victim if she called 911, according to police.
Officers arrived on the scene and entered the home's open garage to find two men, identified as Rocco Moore, 34, of Concord and 28-year-old Richard Jobe, police said.
Police said Moore reached for his waistband and hid behind a mattress while Jobe refused to follow the officers' commands and began fighting with them.
According to police, a dog in the garage charged toward the officers, who shot and killed the animal.
At some point Moore stopped hiding and complied with police. Police said the officers were able to subdue Jobe, who was taken to a hospital with injuries he suffered during his struggle with the officers.
The female victim told police that Moore had beaten her and held her against her will, police said.
Both suspects were arrested on suspicion of multiple crimes and taken to county jail in Martinez.