State Fire Marshal Stephan Coan described yesterday as "a good day" of investigation but declined to discuss specifics. Officials are trying to determine what caused the explosion Wednesday morning in a building that housed two companies that manufactured ink, adhesives and coatings, CAI Inc. and Arnel Co. The blast destroyed almost a dozen homes and damaged many more in Danversport.

The U.S. Chemical Safety Board, an independent federal agency that investigates industrial chemical accidents, has yet to begin its investigation since being denied access by Danvers fire Chief James Tutko.

The five-member federal team arrived on Friday and spent yesterday considering its options - including legal action - to get access to the blast site, according to a spokesman.

"We intend to conduct our investigation and we remain confident that we'll be able to do that," said Daniel Horowitz, spokesman for the Chemical Safety Board.

Tutko said on Saturday that the board has no regulatory authority and should serve only as a resource to state and local investigators.

"They're not a piece of the pie," he said.

Tutko also disputed the federal team's assertion Friday that the investigation could take up to a year, saying several days is more accurate.

Danvers Deputy fire Chief Kevin Farrell yesterday declined to speculate how long the investigation might take. The site of the explosion is an active fire scene being investigated by the State Fire Marshal's Office, the Bureau of Alcohol, Tobacco, Firearms and Explosives and Danvers fire investigators Lt. David Deluca and Capt. Frank Sacco.

"When we finish our (investigation), they can do whatever they want," Farrell said of the Chemical Safety Board.

As investigators looked into the cause of the explosion, building inspectors, along with structural engineers, electricians and plumbers, went from house to house during the weekend checking the chimneys, gas lines, electrical service and plumbing of the affected buildings.

Six families were able to move back into their houses on Riverside and Bates streets yesterday. Town Manager Wayne Marquis declined to give a firm date for when others would be allowed to move back into their houses and instead said it would have to be determined on a "case-by-case" basis.

On Saturday, south of the Porter River, 16 residents of the New England Home for the Deaf's Thompson House, an assisted-living facility, returned home.

"I'm so excited! I missed my home," Beatrice Crowley said through an interpreter.

Crowley and her husband, Bill, have lived in the Thompson House for two years.

"I really thank God He gave me this place," she said.

Throughout the weekend, displaced residents packed Town Hall, where they filled out forms with the Massachusetts Emergency Management Agency and received counseling and support from Red Cross and Salvation Army workers. More than 130 people had registered with MEMA as of Saturday night - enough, Marquis hopes, to qualify for federal disaster relief.

For that to happen, Gov. Mitt Romney would need to declare a state of emergency.

Romney spokesman Eric Fehrnstrom said administration officials worked on the matter throughout the holiday weekend and may have an announcement about an emergency declaration as early as today.

If enough small businesses and residents report losses not covered by insurance, Danvers could qualify for federal loans from the Small Business Administration, said MEMA spokesman Peter Judge.

"It's not a slam dunk," Judge said. "It depends on what percent of the loss is uninsured."

Material from The Associated Press contributed to this report.