STRASBURG, Pa. — A Pennsylvania mother bought a firearm the day before she and her two young children were found shot to death in their burning home, authorities said Tuesday.

Officials said they don’t believe there was any further danger to the community following the discovery of the bodies of Carola Arnau, 40, her 10-year-old daughter and her 4-year-old son in their Strasburg home.

“I tell people, in my job, some days are worse than others, and this is one of the worst, and certainly one of the darkest,” Lancaster County District Attorney Craig Stedman said during a news conference.

Emergency responders were called to the home at about 3:20 a.m. Tuesday and found the bodies of the three in their beds in a bedroom. The family dog also was found dead. Stedman said the fire was believed to have been deliberately set.

A firearm was found on Arnau, who had purchased a gun Monday along with some ammunition which authorities said was accounted for. Stedman said authorities were interested in learning about her mental state from relatives and others.

Arnau’s husband, he said, had been at work from 10 p.m. the previous evening “and would have not been present at the time of these offenses.” He was cooperating with authorities and Stedman offered his condolences to him.

Stedman said the couple had been going through “somewhat of a bitter divorce” and the situation had been “escalating.” Stedman said he wasn’t releasing the names of the children because he was concerned their classmates could hear of their deaths in television reports.

“I am so tired of so many absolutely senseless things,” Stedman said. “Whatever disputes you have in your life and whatever issues you’ve got, when you see and learn news about children being murdered — there’s just no question that they were murdered — that takes it to a different level,” he said.

He said the “only small comfort” is that the children appeared to have been shot in their sleep.

Authorities still must complete a forensic reconstruction of the crime scene amid the arson, autopsies on the three family members and a psychological history of Arnau, Stedman said. They also have to confirm that the gun found with her was the source of the gunshots.

“All indications would be that that was the gun, but I can’t tell you that for sure,” Stedman said. There was no indication of a note at the scene, he said.

State police Lt. Brandon Daniels said there was no further danger to residents of the borough, located about halfway between Philadelphia and Harrisburg, the Pennsylvania capital.

Ron Rannels, 70, who lives nearby, described the family as “very nice,” and recalled seeing the father pulling the two children down the street in a wagon, stopping by his house to pick flowers for their mother.

“I’ll tell you it’s really tough. They were so nice. … Everybody got along with them,” Rannels told LNP newspaper.