A Big Rock, Ill., firefighter was found dead at the bottom of her basement stairs with large bites around her neck. A mastiff she and her husband adopted just a week earlier killed Dawn Brown. She was 44.

Her husband Bob, also a full-time firefighter, found her. The couple also owned a pit bull mix and a boxer and decided to bring in the mastiff when a friend with small children felt unsafe with the dog in their home, according to the New York Daily News. The Browns did not have kids of their own.

Kane County Sherriff’s Lt. Pat Gengler told the Chicago Sun Times it took four police officers to get the animal under control. The dog was estimated to weigh 130 to 150 pounds, “all muscle, very intimidating,” he said.

“As soon as they got there it was obvious that she had passed away,” Gengler said. “We saw there were three dogs: a mastiff, a boxer and a pit bull mix. I'm not sure, but the mastiff was the issue. We processed the scene and waited for the autopsy. It came back that the injuries, the bite marks, were definitely from the mastiff. His jaws are so much bigger than the other dogs'.”

Officials said they had “no idea what caused the attack.”

While the public, fairly or not, is used to seeing pit bulls in the news for attacking humans, it might be a surprise for the offender in this case to be a mastiff. The large dog can be intimidating because of its sheer size, but mastiffs are usually a threat only if they’re in pain or feeling territorial. Dogs also can develop a predatory instinct, a rare occurrence but serious nonetheless.

“It’s really more of an issue of the individual animal,” said veterinary behaviorist John Ciribassi, who did not speculate on the cause of the attack on Dawn Brown.

“To pronounce one of your own dead is probably one of the hardest things we have to do,” Capt. Debra Raymond, who responded to the scene, told the Chicago Tribune. “We’re like an extended family.”