Firefighters sprayed a foam blanket on the smoldering ruins of the building late yesterday afternoon in an attempt to smother any remaining flames. Once the fire is completely out, Danvers Fire Chief James Tutko said, investigators can begin the process of combing through the rubble to look for clues.

State Fire Marshal Stephen Coan said there is no reason to suspect foul play.

"There are no red flags. There were no threats," Coan said. "There was no indication that this was anything but a robust business."

Tutko said there is a possibility that the cause will never be determined because of the extent of the damage.

The building where the explosion occurred was home to two chemical manufacturing businesses, CAI Inc. and Arnel Inc. The companies make cleaning solvents and ink by mixing "volatile" and "highly flammable" chemicals, Mike Nalipinski of the Environmental Protection Agency said.

Coan said the force of the blast, which shattered windows a mile away in downtown Danvers and was heard as far away as New Hampshire, was remarkable in its scope. But, he said, even a relatively small chemical plant can cause a huge blast if the chemicals are mixed improperly.

"At times it doesn't take that much volume of chemicals when they're mixed to cause a violent explosion," Coan said.

Fire alarm sounds

Tutko said a fire alarm in the building on Water Street went off at 2:46 a.m., followed seconds later by an explosion. Residents said there were as many as four explosions, followed by a huge wall of flames that rose above the rooftops of nearby homes.

"I didn't know if we were having an earthquake or a plane was hitting us," said Linda Carney, who lives on Bates Street with her husband, Paul. "As I'm running downstairs, I heard neighbors screaming. I didn't know if it was a terrorist attack."

Residents described surreal scenes inside their homes: Of being awakened from their sleep to see windows shattering, doors ripping from their hinges, walls collapsing, ceilings falling and even furniture flying across the room.

Kelly Lord, who lives at 12 Bates St., across the street from the chemical plant, said she was awakened by the explosion, then was struck by a window frame and her bedroom bureau. The bureau hit her in the face, creating a cut that required butterfly stitches on the bridge of her nose.

"Everything imploded," she said. "My house is totally destroyed."

Outside, neighbors ran through the darkened streets wondering what had happened. Some people thought it was a plane crash. Others suspected some sort of a terrorist attack.

Wayne Begonis of Riverside Street said he saw one man running down the street in his boxer shorts carrying his dog.

"Apparently his house was leveled," Begonis said. "He said, 'That's all I have.'"

'He was wonderful'

Despite the chaos, residents told stories of neighbors helping neighbors. Begonis ran next door to help an 80-year-old woman whose damaged door was jammed. Carney said one of her fellow Bates Street neighbors, John Joyce, assisted an elderly couple, then ran to her house to make sure she and her husband got out OK.

"He was wonderful," Carney said.

More than 100 firefighters from 30 communities eventually poured into Danvers. Because of the possibility of another explosion, firefighters fought the blaze with large hoses from a "faraway distance," Tutko said.

Once the fire was contained, officials decided to let the chemicals burn off rather than risk washing more chemicals into the nearby Danvers River, Tutko said.

Coan, the state fire marshal, called the force of the explosion "very unusual." He said steel structures from the chemical plant were found lying in the neighborhood.

"I can't think of an explosion in recent times that extended to this many buildings," Coan said. "To think that people got away from that with cuts and bruises is just a miracle."

Gov. Mitt Romney, who held a press conference in the middle of Water Street, said Coan told him that more serious injuries were averted because the explosion took place in the middle of the night when people were in bed, allowing them to avoid flying glass and debris.

"Had they been standing up, it could've been a very different story," Romney said.

Romney said officials will explore every possible source of aid for residents and the town of Danvers. He left open the possibility of declaring a state of emergency in Danvers, although he said that "doesn't appear to be immediately required."

Peabody damage

The damage even extended to adjacent Peabody. Mayor Mike Bonfanti said he heard reports of windows broken in downtown Peabody by the blast. Closer to the epicenter, Peabody resident and City Hall worker Frank Nguyen reported that his basement bulkhead had been blown away, according to the mayor.

Danvers officials allowed some residents to return to their homes to gather their belongings, but others were not allowed back in. Town Manager Wayne Marquis said Riverside and Bates streets will be closed for "several days" until inspectors can assure the safety of the damaged homes.

Marquis said Town Hall will be open at 10 a.m. tomorrow and Saturday with federal, state and local officials available to help residents affected by the explosion.

The future is uncertain for many in the neighborhood, including Mary Scorzoni of Riverside Street. Her home received relatively minor damage, but it came at a particularly bad time. She is scheduled to close on the sale of her house Wednesday.

"I'm hoping the guy still wants that waterfront property," she said.