Four people in Queens, including the parents of an NYPD sergeant, were found dead in their home Friday, and carbon monoxide poisoning is likely to blame. NY1's Polly Kreisman filed the following report.

Shielding them with sheets, police removed the bodies of 83-year-old Jerry Hugel and his wife, 80-year-old Marie Hugel, from their home in Floral Park Friday evening.

Sources say it was their son, an NYPD sergeant, who found his parents overcome by carbon monoxide.

"Shock, shock," said neighbor Helga Harter. "The biggest shock of my life."

Police say Jerry Hugel was found near a running car in the attached garage. His wife and two other victims - a tenant and a family friend, both in their 70s - were found inside the house.

"A great couple. That's all I can say. Just a great couple," Harter said.

Harter was part of the same Bavarian Culture and Dance Group that the Hugels belonged to and which often met in a restaurant in nearby Franklin Square, Long Island.

Jerry, a past president of the group, is seen in video participating in a 2011 dance competition.

Other neighbors describe a couple patriotic about their adopted country as well.

"In the spring days, summer, we used to walk by with my daughter and my wife," said neighbor Ramon Rivera. "They were outside. They always had the flag up on Flag Day. Very nice couple. It's very tragic."

"They used to wave, and I would say hello back," said one child.

Carbon monoxide can't be seen or smelled.

There have been two other deadly carbon monoxide incidents this week - one in Maryland and one in New Jersey - and elected officials are stressing how important it is to have a working carbon monoxide detector.

Meanwhile, neighbors in Queens are just trying to come to grips with the loss.

"You just know who they are," said one neighbor. "I am so sorry that this happened because it could be me. It could be my family.

In a statement, the sergeants' union says their thoughts and prayers are with the Hugel family at this terrible time.