The family who lived in the corner house of the cul-de-sac near Frying Pan Farm Park was known as the neighborhood greeters, with the parents waving hello to passersby and the two sons often kicking around a soccer ball.

On Tuesday, the four members of the Peterson family were found dead in their home at 13391 Point Rider Lane in Herndon in an apparent murder-suicide, a law enforcement official said.

"They were your typical American family," said neighbor Jeremy Wilcox. "They were quiet, friendly, very friendly."

Officers were called to the house at 10:30 a.m. after co-workers asked authorities to check on the family after one of the parents hadn't shown up for work on Monday or Tuesday, said Fairfax County police spokeswoman Lucy Caldwell.

(Read more about a vigil scheduled for Wednesday evening)

Police entered the home around noon and found the four bodies.

Police declined to identify the family members, but The Washington Examiner has confirmed through neighbors and public records that the family was Albert and Kathie Peterson and their two sons, Matt, a sophomore at Westfield High School, and Chris, a Rachel Carson Middle School student.

Police would not say how the family was killed, but they said nobody in the neighborhood was in danger, and authorities were not testing for carbon monoxide or any other poisonous gas.

"Detectives feel that the situation was contained within the house," Caldwell said.

(See more photographs from the scene)

Wilcox said he last saw the Peterson family at a neighborhood picnic at 5 p.m. Sunday, where the father spoke with residents while his two boys played soccer with other children before Kathie drove them home.

On social media, classmates were expressing shock Tuesday over the death of their schoolmates.

"Matt rode my bus and I never paid much attention to him. really wish I did now," said someone with the Twitter handle @madiemasonn.

"Life can change in a second appreciate it," said another, @DSosa10.

Neighbors said the Petersons moved into their house more than 20 years ago and were always pleasant to speak with.

The family was always working in the yard, on the porch waving at cars or barbecuing, neighbors said.

Sherry Webster, who lives near the Petersons on Point Rider Lane, said they were a cute couple and described Al as a "big, burly guy" and called Kathie "always full of energy and talkative."

Albert, 57, worked in the information technology business, and Katie, 52, once ran an office supply business out of her home, neighbors said.

Whenever it would snow, the father would strap a plow onto the front of his pickup truck and drive around the block to ensure his neighbors could get to work.

Police did not release the family's cause of death because the investigation was ongoing.

Ed Swanson, who lives several houses down from the Petersons, said he never saw any trouble with the family.

"This is a nice, quiet neighborhood," Swanson said. "The police are never called out here. This is tragic."