A man who killed his estranged wife and two children before taking his own life this week went to the home armed with a pair of guns and a knife, investigators said Thursday.

Steven Lake left no suicide note at the scene, so his motives may never be known, said Stephen McCausland, spokesman for the Maine Department of Public Safety.

Lake went to the home prepared for confrontation Monday, bringing with him a 12-gauge shotgun used in the killings, as well as a .22-caliber handgun, extra ammunition, a knife and a flashlight, McCausland said. He also spread flammable liquid believed to be diesel fuel in the house, but it didn't ignite, police said.

"There's little doubt he had a plan," McCausland said.

Investigators are still trying to determine where Lake got the guns, McCausland said. Because of court orders, Lake was not allowed to have a gun or to be near his family.

Lake's funeral was scheduled for Friday in Skowhegan. A funeral will be held Saturday for his wife, Amy Lake, and their two children, 12-year-old Monica and 13-year-old Coty.

Investigators spent part of the day Thursday searching Steven Lake's home in Wellington. As for Amy Lake's home in Dexter, McCausland said it was unclear how Steven Lake got inside. There was no sign of forced entry, though one of the doors was smashed by the tactical team, he said.

Police were alerted to potential trouble after someone who works at the school where Amy Lake taught kindergarten saw Steven Lake's vehicle parked outside.

The first officer who arrived at about 8 a.m. heard gunshots; two more shots were heard when a backup officer arrived. Investigators believe those were the fatal shots.