THE BRONX - A second suspect in connection to a deadly house explosion in Kingsbridge was held without bail at his arraignment Thursday.

Prosecutors say inside the home on West 234th Street was a sophisticated and elaborate marijuana operation that was hidden from public view. 

The home lab, prosecutors say, consisted of three floors filled with pots of marijuana plants, some the size of small trees. 

Prosecutors revealed the allegations during the arraignment of Garivaldi Castillo, the second suspect connected to the blast that killed FDNY Battalion Chief Michael Fahy.

Investigators say the house was tightly insulated with plastic bags covering the windows to seal in heat. They say liquid fertilizer — considered highly flammable — and a full-sized helium tank were also found in the three-story home. The Bureau of Alcohol, Tobacco, Firearms and Explosives is one of the many agencies now part of the ongoing investigation.  

Julio Salcedo-Contrer, the other suspect and the man who police believe rented the home, waived his right to an extradition hearing in New Jersey. He will be transferred to New York for further prosecution.

Police say Salcedo-Contrer ran off when firefighters arrived Tuesday morning and smelled gas.

Castillo is due back in court on Oct. 4.

Neighbors near the site of the explosion are still waiting for utility companies to restore power, hot water and gas.