KINSTON, N.C. — Investigators entered the hulking ruins of a medical supply factory Saturday, while relatives mourned one of four people who died as a result of the explosion that demolished the building.

Investigators in white helmets and protective coveralls circled the remains of the West Pharmaceutical Services Inc. plant early Saturday as firefighters poured water on smoldering areas.

"There's hot spots here and there; it's just mainly containing them," said Mike Morris of the Lenoir County Fire Command. "It's going to smolder for days."

Despite the unsafe condition of some of the building, Peter O'Connor, a special agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives, said investigators went inside Saturday.

They brought along dogs who sniffed for evidence of accelerants and examined the patterns of damage, O'Connor said.

He said the time allowed them to rule out some causes for the explosion, but he declined to reveal them.

The investigators also got into the chemical mixing room, where the fire is believed to have started.

"The investigation should be completed in the next several days, when we hope to have a preliminary cause and origin," O'Connor said.

The blast shot flames and debris high into the air and shook buildings miles away Wednesday.

Some investigators have theorized that dust produced in the rubber-making process might have ignited somehow. But others have said it's too early to speculate.

About 130 people were inside the plant at the time of the explosion. Nine remained hospitalized Saturday at the North Carolina Jaycee Burn Center in Chapel Hill.

One burn victim died Friday; three other people were killed in the blast's immediate aftermath.

Dozens of relatives and friends came to a downtown funeral home Saturday to mourn Faye Wilkins, who died near the beginning of the disaster when she was trapped in the plant by fallen steel beams.

Wilkins, 50, and her estranged husband had two sons and a daughter and three young grandchildren. She had worked at West for 17 years.

Family friend Angela Brown said it has been hard for Wilkins' loved ones to accept her death and those of the others.

"A lot of people are mad that this had to happen to these people," she said.

William Gray, 51, and James Byrd, 60, of Dover, were also killed outright.

Kevin M. Cruiess, 22, of Kinston, died Friday at the North Carolina Jaycee Burn Center in Chapel Hill.

Childhood friend Nancy Jackson Carlin said she last saw Wilkins when they ran into each other at the doctor's office shortly before Christmas.

The two women and two other longtime friends had since talked about going out together, Carlin said.

"We planned to go out and get something to eat and go dancing," she said. "We all loved to dance."

Wilkins was the kind of woman who was always happy and enjoying life, said Sissy Schrader, who felt her friend's loss keenly.

"This is very hard on all of us," Schrader said. "It's very hard."