Reports at the time were saying "pistol" although the police never publicly confirmed what sort of weapon was used. An eye witness was quoted as saying:
"She ran right out into the street and was pounding on cars," said David Gosh of West Allis, who had been returning from duck hunting earlier Sunday with his father, John, and a friend, Ben Luedke.
Gosh said that moments later, a man with a handgun ran out and appeared to be chasing the woman.
Just then, Gosh said, police began streaming to the scene, and the gunman, seeing them, ran back into the building."
I found no reports of a rifle used in the killings.
Regards,
GtG
I had to search but I found an article that said he was able to illegally buy a semi-auto rifle several days before the killings. I assumed that was the weapon he used. I have since found an article that said it was a 40 cal semi handgun. I stand corrected.