LAWRENCE, Mass. — City officials will meet tomorrow with the owners of the Merrimac Paper Co. building that was ravaged by fire Friday night to determine how soon the mill can be demolished.

"Our goal is to get the building down as soon as possible because it's unsafe," said Myles Burke, the city's inspectional services director. "We can't leave a weakened building that way for a long time."

He said the building's owners were at the scene yesterday morning.

"In talking with them, they seem very willing to secure the property," Burke said.

The 200,000-square-foot building on South Canal Street went up in flames around 7 p.m. on Friday. It was known as a refuge for the homeless, and police said they are still looking for a man who was often seen in and around the property.

The gas, electricity and water had been shut off in the 146-year-old building, as well as the sprinkler system. The boarded up building had been under a fire watch.

Burke said Merrimac Paper Co. has a water lien of more than $400,000 that would prevent owners from pulling any permits. However, he said it can be waived to allow the owners to hire a demolition company to tear down the building.

"It will be to aid search and recovery efforts, and it wouldn't go any further than that," he said. "We don't want to see anyone involved in a search or retrieval mission get hurt."

Meanwhile, police and fire officials are keeping a 24-hour watch on the site.

Fire Chief Peter Takvorian said his department is still investigating the cause of the blaze. He said the fire might have started in the middle of the building, because that area had the worst fire damage, including deep charring of wood beams and general structural damage of the steel.

He said investigators are focusing on the second floor because witnesses had reported homeless people living in that area of the building.

At the height of the blaze, the second and third floors were heavily involved, with flames shooting 100 feet above the roofline. Firefighters did not enter the building due to concerns that the roof would collapse, which it finally did around 9 p.m.

When the roof caved in, Takvorian said there were fears that embers might fly to the roof of the paper company's newer building.

"We kept putting a coating of water on that roof as well to keep the fire from communicating with that building," he said.

Fire and city officials had long worried about a fire at the vacant mill building.

"This was an accident waiting to happen," fire Capt. Kevin Loughlin said. "When we tell people to keep their sprinklers on, we do it for a reason."