Officers soon arrived at the apartment and found a woman bleeding outside the unit, the department stated. Hearing the cries of the toddler inside, police entered the apartment to find Thapa kneeling over his son-in-law after stabbing him with a 10-inch curved dagger.
Thapa was ordered to drop the knife and surrender. In body camera footage, Thapa is seen about to stab his son-in-law again when officers opened fire, fatally shooting Thapa.
Following the shooting, one of the officers is seen picking up the child, who had been in front of Thapa at the time. The boy was uninjured and taken into protective custody before an appropriate family placement was arranged.
Thapa's wife and daughter were rushed to the hospital, where they were pronounced dead. The son-in-law was also taken to the hospital, and he was in critical condition.
Thapa, a native of Nepal, had no criminal record, and investigators are trying to determine a motive. According to the son-in-law, Thapa might have suffered from mental health issues.
"I wonder if our (officer) … stopped a quadruple murder from happening," Chief Kevin Davis said at a Thursday news conference.
"As bad as it was, it could have been a lot worse," he added.