A firefighter who was critically hurt as he was preparing for a drill at his Brooklyn firehouse is not expected to survive his injuries, officials said Friday.

Firefighter William Moon II, 47, fell around 20 feet inside Rescue Company 2, on Sterling Place in Brownsville, around noon on Monday, Mayor Eric Adams and FDNY Commissioner Laura Kavanagh said in a statement Friday morning.

He was taken to NYC Health + Hospitals/Kings County with a serious head injury and "will not survive his critical injuries," the statement said.

"His family has made the decision to donate his organs to save the lives of others," the statement added.

The firefighter has a wife and two children, according to the statement.

At a news conference Friday morning, FDNY Chief of Department John Hodgens called the incident a “heartbreaking, tragic accident.” 

Moon joined the FDNY in 2002, the statement said. He moved to Rescue Company 2 earlier this year after working at Ladder Company 133 in Jamaica, Queens for two decades.

The Islip, Long Island resident was also a member of the Islip Volunteer Fire Department.

"This is a heartbreaking loss for New York's Bravest, and for our entire city," Adams said in a statement. "Firefighter Moon was a dedicated public servant, who spent more than two decades saving the lives of New Yorkers and will continue to do so in his passing."

"Our hearts are broken for Firefighter Moon's family and friends, and for our entire department," Kavanagh added in her own statement. "Firefighting was in his bones, and he embodied the spirit and passion of our department."

Uniformed Firefighters Association president Andrew Ansbro, whose union represents thousands of active and retired FDNY members, called the Monday incident “a devastating tragedy that breaks the hearts of each and every member of the FDNY Firefighter family.” 

“Firefighter William P. Moon spent his life and career saving the lives of New Yorkers, and to learn of the donation of his organs, he will also do so in his passing,” Ansbro said. “With more than two decades in the department, Firefighter Moon was an exemplary member of the FDNY, whose contributions to his fellow firefighters, the department, and this city will never be forgotten.”