Boston police are investigating after one person suffered life-threatening injuries and another was seriously injured in a dog attack Monday night in Roxbury, the department said.

Officers responded to a report of a dog attack on two people around 4:49 p.m. at 35 Dennison St., police said. Inside the home, police found two adults, a woman and a man, suffering from injuries sustained in the attack. Police said the dog was not inside the residence at the time.

Police said that while officers were assisting the two victims, the dog returned and attacked two of the officers who responded outside the residence. One of the officers fired his gun at the dog, hitting it.

The two victims, who officials believe are relatives and the owners of the dog, were taken to a local hospital. Police said the woman suffered life-threatening injuries, while the man is suffering from “very serious injuries”.

The two officers were taken to a local hospital with non-life-threatening injuries, police said.

The dog involved in the attack is alive and has been taken from the scene by animal control, police said. Three other dogs were also taken from the scene.

Police said parallel investigations into the incident are ongoing. The homicide unit is investigating due to the severity of the injuries. They will work alongside the department’s Discharged Firearms Investigation Team, which was called in because of the officer who fired at the dog, police said.

The department is asking anyone with information about the incident or a history of the dog to contact investigators at 617-343-4470 or the tip line at 1-800-494-TIPS.

Monday’s incident is the second dog attack Boston police have reported in the past week. Police answer last monday to a report of a dog biting a person in Dorchester. The dog in that incident was shot by police and later died from its injuries. The person bitten by the dog was hospitalized with non-life threatening injuries.