Two teenage siblings found shot to death in a Meeker County house on Monday died as a result of a murder-suicide, officials said.

David L. Cunningham, 17, shot his sister, 15-year-old Jessica K. Cunningham, before turning the gun on himself in their family home in Harvey Township, according to a sheriff's office news release.

David, a student at Atwater-Cosmos-Grove City High School, was home Monday because there was no school that day. Jessica, a former student at the school, had been schooling on-line at home.

Their father, Thomas Cunningham, 51, came home to find the two deceased. Deputies were called to the house about 2:35 p.m.

Sheriff Brian Cruze said authorities didn't have any indication of a motive on Wednesday.

"That's the mystery right now," Cruze said. Deputies will be "backtracking David and his life the past few weeks."

Officials executed two search warrants Tuesday at the residence on 340th Street. One was for a follow up on the murder-suicide investigation. A separate one was for "marijuana and marijuana grow related items," the sheriff's office statement said.

The drug case and the murder-suicide case did not appear to be related, the statement said.

The Minnesota Bureau of Criminal Apprehension is assisting in investigating the deaths.