Investigators are looking into possible foul play after the deaths of four people found in a burning house in Northwest Washington on Thursday. (WUSA9)

(Update: Probe continues into mysterious deaths of four in burning D.C. home)

The mysterious deaths of four people found in a burning house in Northwest Washington on Thursday afternoon prompted police to ask the public for help in investigating what they called a highly suspicious fire.

Police said that three adults and a child, whose identities were not released, were discovered on the second floor of a home on Woodland Drive NW, just north of the vice president’s residence at the U.S. Naval Observatory. Police did not say how they died.

Police Chief Cathy L. Lanier said that detectives were trying to track the movements of a blue 2008 Porsche, with D.C. license plates, that disappeared from the home Thursday morning and was found abandoned by 5 p.m. She said there were no signs that anyone had broken into the home.

Family members said the home is owned by Savvas P. Savopoulos, a 46-year-old corporate executive, and his wife, Amy, who is active in Washington’s society circles and fundraising events. The couple have three children: two teenage girls — one is a senior at a Pennsylvania boarding school who is scheduled to graduate next week — and a younger boy.

“We don’t know what is going on,” said Debra Ann Masser of Sarasota, Fla., the sister of Savvas Savopoulos. Masser said family members had been reaching out to authorities to figure out who the victims are but that they have not received any answers. She declined to discuss the fire or family further until she knew more about what happened.

Philip Savopoulos and James Martin, the fathers of Savvas and Amy Savopoulos, said that as of 6:30 p.m., they had not received word from authorities about the victims’ identities. Both were too distraught to speak further.

The fire was reported about 1:15 p.m., and firefighters found flames coming from the home’s shingled second-floor roof. They broke windows, went inside and found the four victims. The cause of the fire has not been determined. It was extinguished within about 30 minutes.

Lanier said a team of officers would go door-to-door in the upscale neighborhood asking residents whether they had noticed anything unusual. Police also passed out fliers saying they were investigating an arson at the home and asking for information. An arson task force that includes D.C. homicide detectives and federal investigators with the Bureau of Alcohol, Tobacco, Firearms and Explosives is involved in the investigation.

“We still have not gone through the extensive evidence-collection process,” Lanier said at the scene Thursday night. There is “not a lot of information at this point.”

Lanier would not say who owns the Porsche, with the license plate DK2418, or where it was found. But she asked anyone who had spotted it to call police.

The Savopoulos’s red-brick house, which has multiple fireplaces and gables on the roof, is on a tree-lined street with manicured hedges near exclusive schools and is a block from the Belgian Embassy.

D.C. Mayor Muriel Bowser arrives to address the media on the scene in the 3200 block of Woodland Drive NW, where four people were found dead at a house fire in Washington. (Ricky Carioti/The Washington Post)

“Smoke was pouring out of the upper story of the home,” said Landon Butler, a neighbor who witnessed efforts to control the fire. “The firefighters were on their ladders to get at it.”

Jacqueline Rizik, another neighbor, said that she saw firefighters carry a woman from the house on a stretcher. Rizik said that it appeared that firefighters tried to perform CPR before the woman was taken away in an ambulance.

Rizik was concerned for the Savopoulos family, whom she said she has known for years. She said that the family is well liked and frequently entertains neighbors and friends at their home.

“They are wonderful people,” Rizik said. “Their kids are well brought up.”

The neighbors said the damage to the house appeared extensive. “They had to break down the front door and windows to get inside,” Rizik said. “Fire and smoke were pouring out of the windows.”

Rizik said the family had lived in the neighborhood for at least two decades. Amy Savopoulos volunteers at several places supporting her children’s schools and causes. The couple is listed in the Social List of Washington D.C., otherwise known as the Green Book, with the home on the 3200 block of Woodland Drive NW and another in Christiansted in the U.S. Virgin Islands.

The couple donated at least $100,000 to National Cathedral School in 2012, according to the school’s newsletter, and Amy Savopoulos served on the dinner committee for a fundraiser for Mercersburg Academy, which is in Pennsylvania, at the Four Seasons hotel this year.

Savvas Savopoulos is listed on the company Web site as president of American Iron Works, a ­Hyattsville-based company that manufactures building materials. His Facebook page says that he is the head of Sigma Investment Strategies, a hedge fund and management company, and that he had recently accepted a job in Puerto Rico.

A person who answered the phone at American Iron Works declined to comment, as did a representative at a law firm in Bladensburg that lists Savopoulos as an attorney. He is a member of a group called the Young Presidents’ Organization, a peer network for executives younger than 50.

Lynh Bui, Aaron C. Davis, Abigail Hauslohner, Magda Jean-Louis, Dan Morse, Aly Seidel, Clarence Williams and Julie Zauzmer contributed to this report.