Police say the standoff started at about 9 p.m. after a report of a possible shooting, with a third party reporting that the man inside the residence had killed his girlfriend.

The police department says the Special Response Team was called to assist and was able to make contact with the man, identified as 58-year-old Brad Swanson of Rapid City. After several attempts to negotiate with Swanson, SRT members were able to make their way inside the residence and found Swanson and his girlfriend, 55-year-old Debra Ohlmacher of Rapid City, with gunshot wounds. No motive has been identified.

Lt. James Johns of the RCPD says, "When you ask somebody to go into somebody else's head, I just don't know. I don't know what leads a person to take this type of action. It's an illogical and tragic event and there's no justification for it."

The investigation into the incident is ongoing, but law enforcement says they believe the case to be a murder-suicide.

-Brendyn Medina