Bronx prosecutors Tuesday said they will ask a grand jury to add assault and possibly homicide charges against two men accused of running a marijuana grow house that exploded Sept. 27, killing FDNY battalion chief Michael J. Fahy.

Both defendants, Garivaldi Castillo, 33, and Julio Salcedo, 34, face felony marijuana possession charges and will also be hit with assault charges based on Fahy's death and injuries to an FDNY lieutenant, officials said.

Prosecutors are also continuing to explore possibly filing homicide charges based on Fahy’s death and the possibility that someone had tampered with a gas main in the building at 304 W. 234th Street in the Kingbridge section of Brooklyn, said a spokeswoman for Bronx District Attorney Darcel Clark.

The NYPD said there had been a leak in the gas line that had shown an unexplained “deviation” in its structure. The gas pipes have been sent to a federal laboratory in Maryland for further analysis.

Police and federal agents had the home on 234th Street under surveillance and after the explosion — which destroyed the two-story building — found numerous marijuana plants, liquid fertilizer and other items used for running a greenhouse, the NYPD said. Salcedo and Castillo were arrested last week and are being held without bail.

A law enforcement source said the second-story windows in the structure had been sealed to keep in heat, something that likely allowed leaking gas to accumulate to a volatile level. Fahy was killed when a large piece of the roof of the house blew off and fell on him. Ten people, including a number of firefighters, were injured.

Neither defense attorney Dawn Florio, who is representing Salcedo, nor Francisco Serrano-Walker who is representing Castillo, could be reached for comment Tuesday.