GLENSHAW — A suburban Pittsburgh electrician fatally shot his daughter and wounded his wife and son before killing himself early today, but police were at a loss to explain why.

Homicide detectives found no sign of a struggle and said they have found no letters or other items explaining why James Edwards, 52, shot his family, their dog and then himself shortly after 3 a.m. inside their Shaler Township home.

“It looks like the children were in their respective rooms. He went from room to room, for lack of a better term, and shot all the people,” Allegheny County police Lt. Andrew Schurman said. “We might never know exactly why.”

The gunman’s wife, Charlene Edwards, was conscious when police arrived and did not mention any marital problems, police said.

The county medical examiner planned autopsies today on Edwards and his slain 19-year-old daughter, Laurin Edwards. Charlene Edwards, 51, and the couple’s 21-year-old son, also named James, were taken to Allegheny General Hospital in Pittsburgh.

They were listed in critical condition but were expected to survive.

Authorities discovered two revolvers they believe Edwards used.

The family had celebrated Laurin Edwards’ birthday on Wednesday.