Police investigators spent much of Tuesday afternoon and evening investigating the deaths of a man and a woman in their home in a North Suffolk riverside neighborhood.

City spokeswoman Debbie George said 911 dispatchers received a call about 3:30 p.m. from a 16-year-old boy who said his mother was injured in the house in the 100 block of Lookout Circle in the Bennett’s Creek Landing subdivision.

Emergency responders found Kathryn Laine, 47, dead inside the home and her husband Stephen Laine, 50, deceased in the garage.

George said police officers had to leave the house after a cursory check because of a high level of carbon monoxide. They opened several windows so the air could clear while they waited for a search warrant.

According to George, the causes of death had not yet been determined, and autopsies were scheduled for today.

Many neighbors arrived home from work Tuesday evening to find their neighborhood swarming with police officers and media. Some who said they knew the Laines well declined to talk, but others said the news was shocking.

“They were very involved with their kids,” said Lora Blount, who has lived across the street for about four years.

She said the couple has a daughter who is about 12, in addition to the 16-year-old son. She believed they also have another son who is in the military and currently stationed in Germany.

Blount said Kathryn Laine was a nurse and Stephen Laine was in sales.

“We’re just all in shock right now,” she said. “They were wonderful people. He was very outgoing and social. If you ever needed anything, they were always willing to help you out.”

Another neighbor, Clayton Watkins, said the couple had lived in the home about 14 years.

“They were very nice and outgoing,” he said. “The kids were with them all the time.”

Watkins said a neighbor had told him the man had killed his wife and then killed himself by running the car in the garage.

“If what I heard happened is true, I’m surprised they could not have thought about the kids,” he said.

The house was decked out for Christmas, with a Christmas tree visible through the front window and red bows in all the windows. A lighted sleigh and reindeer were on the front lawn. A television could be seen playing through an upstairs window, and the garage sported a “Men at Work” sign above an assortment of tools.

An older-model car was in the garage, as well as a van, sports car and pickup truck in the driveway.

George said the children were with relatives, and a neighbor was caring for the family dog.

If the incident is ruled to be a murder-suicide, it would be the second in Suffolk in only five weeks, and the third in less than three years.

On Nov. 8, 39-year-old Deborah Marlo Wigg was shot by her estranged husband, Robert Lyndon Wigg, 43, who then killed himself in front of her parents’ house.

On March 28, 2009, 57-year-old Jeanette Brabrand shot and killed her former boyfriend, Paul Bamberg, 53, in the study of her Riverview home before killing herself in a bedroom.