Police have no known suspects and are urging extreme caution following the murder of eight people in a dingy mobile home Saturday on the site of a historic plantation in southeast Georgia.

"We are not looking for any known suspects," said Glynn County Police Chief Matt Doering during the second day of investigations into grisly mass murders he called a "horrific" scene unlike any he has encountered in 25 years of police work.

A tight-lipped Doering did not divulge the details of the murders, saying he was "absolutely certain — 100 percent — what happened," but refusing to speak before the family of the surviving victims, both in critical condition in a Savannah hospital, were brought up to speed.

As investigators toll long hours and medical examiners take on the slow labor of performing autopsies on the deceased, Doering told reporters that police officials are working to piece together a baffling puzzle that has left them few clues to the motive for the murders.

"Now the question is who is responsible and ... what would motivate someone to do this?" he said.

"We just simply don't have a whole lot to go on."

The family member of some of the victims who called 911 Saturday morning after discovering the crime scene was arrested late last night on drug-related charges, though police said he was not a suspect in the killings.

Guy Heinze Jr., 22, a relative of those found killed, was charged with illegal possession of prescription drugs and marijuana, tampering with evidence and making false statements to police, Doering said. Doering did not know whether he had an attorney.

Most of the victims were related to Rusty Toler, a poor resident of the New Hope Plantation trailer park nestled among centuries-old, moss-draped oak trees in Brunswick, Ga., a law enforcement source told the Florida Times-Union.

Toler and three of his four children are among the dead, the paper reported. A fourth child is hospitalized in critical condition, a source with intimate ties to the family said.

Investigators were talking to neighbors about whether they saw or heard anything unusual at the dingy mobile home shaded by large, moss-draped oaks with an old boat in the front yard. Police had not interviewed the survivors, who remained in critical condition Saturday night and may be the only witnesses.

"I assume they know something, but we have not been able to speak to them," the chief said.

All seven bodies were tentatively identified by Saturday evening. Doering said families of the victims had been notified, but he would not release any names or ages before receiving the autopsy results.

"I really don't know the ages," Doering said. "There were some older-aged victims and we believe there were some in their teens."

Located a few miles north of the port city of Brunswick, the mobile home park consists of about 100 spaces and is nestled among centuries-old live oak trees near the center of New Hope Plantation, according to the plantation's Web site.

The 1,100 acre tract is all that remains of a Crown grant made in 1763 to Henry Laurens, who later succeeded John Hancock as president of the Continental Congress in 1777.

Laurens obtained control of the South Altamaha river lands and named it New Hope Plantation, according to the plantation's Web site.

Lisa Vizcaino, who has lived at New Hope for three years, said the management works hard to keep troublemakers out of the mobile home park and that it tends to be quiet.

"New Hope isn't rundown or trashy at all," Vizcaino said. "It's the kind of place where you can actually leave your keys in the car and not worry about anything."

Vizcaino said she didn't know the victims and heard nothing unusual when she woke up at 7 a.m. Saturday morning. After word of the slayings spread, she said, the park was quieter than usual.

"Everybody had pretty much stayed in their houses," Vizcaino said. "Normally you would see kids outside, but everybody's been pretty much on lockdown."

Click here for more on this story from the Florida Times-Union.

The Associated Press contributed to this report.