GRAPEVINE, Texas: Seven people believed to be related had opened their Christmas gifts and started cleaning up the wrapping paper when they were shot to death in a suburban Texas apartment, police said Sunday.

Authorities said they believe the shooter is among the dead, but got a warrant before doing a full search on the small chance that it was otherwise.

Four women and three men, aged 18 to 60, were found in an adjoining kitchen and living room area when police entered the apartment around midday, said Police Sgt. Robert Eberling. Two handguns were found near the bodies in the apartment that was decorated for the holiday with a tree, he added.

"It appears they had just celebrated Christmas. They had opened their gifts," Eberling said.

The victims have not yet been identified, but Eberling said it appears they all died of gunshot wounds. He said authorities still don't know what sparked the incident.

Grapevine Police Lt. Todd Dearing said investigators believe that all the victims were related, but that some were only visiting and didn't live in the apartment. He said police are looking for other relatives to inform.

"Seven people in one setting in Grapevine, that's never happened before. Ever," Dearing said.

He said police were performing a "meticulous" search of the apartment and he expects them to be on the scene for many hours.

Police and firefighters first rushed to the Lincoln Vineyards complex after receiving an open-ended emergency services call at about 11:30 a.m., Eberling said.

"There was an open line. No one was saying anything," he explained.

So police went into the apartment, located in a middle-class, suburban neighborhood of Grapevine, not far from the upscale Fort Worth neighborhood of Colleyville. The apartment is at the back of the complex, overlooking the athletic fields of Colleyville Heritage High School.

But many of the nearby apartments are vacant, and police said no neighbors reported hearing anything on a quiet Christmas morning when many people were not around.

Jose Fernandez, a 35-year-old heavy equipment mechanic who moved to the complex with his family about six months ago, said he always felt safe in the area, but is now afraid to let his 10-year-old son play freely outside.

"This is really outrageous especially on Christmas," said Fernandez, who was visiting family for the holiday and returned to find several police cars parked outside his home.

"This has shocked everybody. It has scared everybody. I guess something like this can happen anywhere, but seven people dead. It's just very scary," he added.

Eberling agreed the area is fairly quiet, noting this would be the first homicide in Grapevine since 2010.

Christy Posch, a flight attendant who moved to the complex about six months ago so her son could attend the high school, said she lives a few buildings away and did not hear any gunshots.

"It's all families. That's why I moved here. No burglaries, no nothing," Posch said.