A man was charged on Wednesday in connection with the house explosion in the Bronx that killed FDNY Battalion Chief Michael Fahy, police said.

Garibaldi Castillo, 33, of Manhattan, has been charged with two counts of criminal possession of marijuana, according to police.

Earlier on Wednesday, Mayor Bill de Blasio had addressed the possible cause of the explosion.

“It’s not confirmed exactly what it was, but there is strong indication it was a marijuana grow house,” the mayor said. 

Another person is also being questioned in connection with the fatal explosion, a police source said. Julio Salcedo was arrested in Cliffside Park, New Jersey, on a warrant for petty crime about 4 p.m. on Tuesday, according to the source. Salcedo has not been charged in relation to the Bronx explosion.

Castillo and Salcedo, who was seen leaving the Bronx house before it blew up, are both believed to be connected to the property, officials said.

Meanwhile, Fahy, a 17-year veteran with the department, was honored by fellow firefighters with a bunting ceremony on Wednesday.

The ceremony was held outside Battalion 19 in the West Bronx, where Fahy was stationed.

FDNY officials said firefighters were called to the two-story home at 304 W. 234th St. in Kingsbridge about 6:30 a.m. on Tuesday for a report of a gas odor. About an hour later, FDNY Commissioner Daniel Nigro said the house exploded, sending a large portion of the roof careening down onto the street.   

Nigro said Fahy had responded to the call and was directing operations in the street when he was hit by part of the roof.

“They evacuated the surrounding buildings. They got everyone else out of the way when the explosion occurred. Chief Fahy was fatally struck," he said.

Fahy, 44, was rushed to The Allen Hospital at NewYork-Presbyterian in upper Manhattan where he was pronounced dead. Another 20 people were injured.

Although firefighters were called to the home for a report of a gas odor and first responders had smelled gas, NYPD Commissioner James O’Neill said police were in "the initial stages of an investigation on that block" based on information they received several weeks ago.

"That's going to be part of an investigation as a possible drug lab," he said.

O’Neill said investigators found marijuana inside the house. "It's a crime scene and it will be for a few days to come," he said.

The exact cause of the explosion remains under investigation, officials said.

At a news conference Tuesday, de Blasio said it was "a very sad day for our city."

“We had a tragedy today," he said. "Tragedy has befallen a family, our fire department and our entire city.”

De Blasio described Fahy as a devoted father of three and “a good man.”

Nigro said the FDNY had lost a hero.

“He was on the rise; he was a star,” the commissioner said of Fahy. “… Our members are all saddened.”

Fahy was a second-generation firefighter, Nigro said. His father, Tom, served as a battalion chief for 33 years, retiring in 2001, according to an FDNY spokesman.

De Blasio said he saw the family's "unspeakable pain" when they learned that they had lost Fahy.

"Our hearts go out to the Fahy family," de Blasio said. "Michael's father, a fire chief before him -- a family that has given so much and today made the ultimate sacrifice to this city.”

De Blasio ordered all flags to fly at half staff Tuesday afternoon in memory of Fahy. All city flags will remain at half staff from sunrise through sunset until Fahy is laid to rest, the mayor’s office said.

The president of the Uniformed Fire Officers Association, Jake Lemonda, released a statement following Fahy’s death, offering the union’s thoughts and prayers to his family and to those who were injured.

“Today we lost one of the best of the bravest,” Lemonda said. “Battalion Chief Michael Fahy made the supreme sacrifice while operating at an alarm in the Bronx.”

Lemonda described Fahy as a “shining star in the department” and said firefighters put themselves in harm’s way to protect lives every day.

Nigro said nine firefighters were injured in the blast, as well as six NYPD officers, two civilians and three Con Edison workers. None of the injuries are life-threatening, he said.

(With Newsday)