DANVERS - As Danvers firefighters squelched persistent embers in the rubble at the Danvers State Hospital site, the company developing the property said yesterday it is determined to rebuild as soon as the smoke clears.

The Easter Eve fire destroyed three unfinished apartment buildings atop Hathorne Hill, where AvalonBay developers are replacing the storied state mental hospital with a sweeping development of 433 apartments and 64 condominiums.

"Absolutely," said Scott Dale when asked if the developers would rebuild. Dale, vice president of AvalonBay, was reached at his home on Easter morning.

"Once the area of the fire has been released back to us - subsequent to the insurance company and the fire department investigation - we will start reconstruction," Dale said.

For the town, it was the second major blaze on the eve of a holiday in less than six months. On the day before Thanksgiving, a Danversport chemical plan exploded in the middle of the night into a ball of flames, displacing an entire neighborhood. Residents there are still grappling with the disaster.

"It's unusual we had two big events in six months," said Capt. Frank Sacco, a 20-year veteran of the fire department. "In this line of business, things sometimes happen in cycles."

Remarkably, no one was killed during the explosion, or during last weekend's fire.

"We were lucky it was unoccupied structures under construction, and that no one was there," Sacco said of Saturday's early-morning blaze. The smoke from the fire was so heavy that State Police had to close Route 1 and Interstate 95.

The fire is still under investigation, and the blaze kept firefighters busy throughout the weekend. Danvers Fire Chief James Tutko likened the fresh construction, which didn't yet have sprinklers, to a lumberyard.

Fire crews are expected to be stationed there until this afternoon.

"There is a lot of masonry there, and bricks and concrete hold heat for a long time," Sacco said yesterday afternoon. "There are so many hot spots still."

The three incinerated buildings were to house 147 apartments, but all that remained were the concrete towers of stairwells and elevator shafts. Dale said the buildings were in various stages of development - at most 60 to 70 percent complete - and would have opened in June or July. No specific tenants were slated to move in, Dale said.

The fire also destroyed three or four garages and utility buildings.

"I guess the only silver lining here is that nobody was injured seriously," said Dale. "The Danvers Fire Department did an excellent job in responding to the fire and protecting some adjacent buildings."

The flames spared the hospital's historic Kirkbride Building except for one charred cupola, which caught fire because of heat radiating from the other buildings.

Firefighters from eight communities responded to the four-alarm blaze.

The looming, spired facade of the 130-year-old Kirkbride building can be spotted from around the area, and what remains of it is being refurbished to accommodate apartments.

The development of the 77-acre site is still in the early stages. The first apartments opened earlier this year, with 48 occupied so far. The development will eventually consist of 433 luxury apartments and 64 condominiums on the old hospital grounds off Route 62.

The site of the fire was fenced off yesterday, and residents living in the new apartments on the occupied side of the AvalonBay development were back in their homes. They had been evacuated to Danvers High School early Saturday morning.

Dale said that in his experience, such fires are uncommon.

"It's a very rare occurrence, actually," said Dale. "We take measures to prevent this type of thing."

Marblehead Highlands, a condominium complex in Marblehead, met a similar fate in November 2005 when a Saturday-morning blaze burned the four-story, 21-unit building to the ground, just a month before residents were slated to move in. And a one-alarm fire last month caused $1 million in damage to the newly constructed Highlands at Dearborn apartment complex in Peabody overlooking Route 128.

Dale said AvalonBay will investigate its safety practices.

"We're conducting our own internal audit to determine what, if anything, we could have done on our end to prevent this," said Dale.

Staff writer Matthew Roy contributed to this report.