The Manhattan district attorney, Robert Morgenthau, is launching an investigation into the deaths of two firefighters over the weekend in a major fire at the former Deutsche Bank building near ground zero.

Prosecutors will join the fire department in the probe. A spokeswoman for Mr. Morgenthau, Barbara Thompson, said it was too early to consider filing criminal charges.

Her comments echoed those of Mayor Bloomberg. “At this point there is no reason for anybody to think in terms of criminal charges or anything else,” Mr. Bloomberg said this morning. “We will continue to act the way you expect us to act. We will do a careful, thorough investigation.”

When asked why firefighters were sent into the burning building on Saturday, even though it was being destroyed, Mr. Bloomberg said people work inside the building during the day and the fire department was uncertain whether people were inside.

What’s more, he added, “You can’t let a fire go out of control,” because it could damage the structure of the building or release contaminates into the air.

When asked in the contractor responsible for the demolition, Bovis Lend Lease, and its subcontractor, John Galt Corp., should be removed from the job, Mr. Bloomberg said, “I don’t know who you would suggest we get.”

“When we went out for contractors to perform this work there was only one contractor willing to take on the job and we are appreciative of that,” he said. “Without that the building would still be at 40 stories.”