Five family members shot to death in home outside Seattle

Authorities have arrested a teenage suspect in what appears to be an instance of family annihilation'

Authorities found five people shot to death inside a home south-east of Seattle on Monday morning and arrested a teenager in connection with the killings, police said.

The killings in Fall City, Washington, were the 25th mass murder in the US so far this year, according to the Gun Violence Archive. The nonpartisan archive defines a mass murder as one in which four or more victims are killed.