Christopher Snyder, 41, shot and killed the three adults inside a neighbor's house in Brookeville, Maryland, about 25 miles north of the US capital, on Monday afternoon, police said, Reuters reported.
His wife fled to the neighbor's house after he held her over the weekend in their own home across the street, Montgomery County Department of Police Chief Thomas Manger said during a news conference.
Three adults, including Snyder's wife, escaped the shooting, he said.
After the shooting, Snyder went back to his house where he barricaded himself inside during an hours-long standoff with police. He shot himself when police entered the house, Manger said.
Authorities were searching Snyder's home after he told police that he had explosives, Manger said.