NEW YORK (CBSNewYork) -- An investigation is underway into what sparked an explosion at a house in the Bronx that killed an FDNY battalion chief.
A police source told CBS2 that a second man was in custody in connection with the blast, which happened Tuesday morning at a home on West 234th Street in what investigators say appeared to be a marijuana grow house.
Garivaldi Castillo, 32, was picked up on Wednesday afternoon, in upper Manhattan, and was being held on an outstanding warrant before being charged with felony marijuana possession.
Firefighters lined the street outside of an NYPD stationhouse in the Bronx and stared down Castillo as he was led to a squad car.
Police sources said the other man -- in custody in New Jersey -- is the same man firefighters encountered leaving the home as they entered to investigate a gas odor Tuesday morning, CBS2's Andrea Grymes reported.
Authorities in Bergen County confirm 34-year-old Julio Salcedo Contrer was in custody and facing a fugitive from justice charge. It is unclear if he was charged in connection with the explosion or with an unrelated case, Grymes reported.
Both men are believed to be workers, and not the brains behind the alleged drug operation.
Investigators worked into the night, collecting bags of evidence at the decimated house where FDNY Battalion Chief Michael Fahy lost his life.
Fahy and several fire units responded to calls of a gas odor at the house around 6:20 a.m. Tuesday. He was on the scene for about an hour, directing operations from the street, when the FDNY said the two-story home exploded.
Fahy was hit and killed by flying debris.
The blast shook the area, exposing what police believe was a possible marijuana farm on the second floor. A source told WCBS 880 that fire marshals are looking into the possibility of an illegal gas line hookup, WCBS 880's Sean Adams reported.
"It's unclear right now whether or not the marijuana grow operation that's alleged to have been here had played any role in the explosion," ATF spokesman Matther Myerson said. "That's one of the things obviously that we'll look at in addition to other possibilities."
As CBS2's Tony Aiello reported, a ConEd leak detection vehicle made a routine drive past the house on Sept. 20, and nothing was found.
On Wednesday afternoon, a heavily damaged car was towed from the blast site.
Jon Williams of the DEA said the combination of chemicals, propane, and the reworking of electrical systems can create a volatile environment.
"The marijuana grow operations are an accident waiting to happen," he said.
As CBS2's Jessica Layton reported, Williams said there are telltale signs that neighbors and landlords can look for.
"A lot of times bulk deliveries of garden supplies, odd schedules of a renter or owner, the windows are typically covered," he said. "Also not uncommon to see a lot of air conditioners delivered or being used."
A law enforcement source told CBS2 that six window air conditioning units were found on the second floor.
The deadly scene has left many people angry in the neighborhood.
"I think it's so damn selfish of people who do this stuff," said resident Mary Yuelys. "Put others at risk, innocent people trying to do their jobs."
Residents are thankful first responders immediately shut down the street that's a popular route for schoolchildren before the explosion occurred.
"I am so grateful to the police department, to the fire department, to Con Edison because my granddaughter was saved yesterday, just like a lot of other kids in this neighborhood," resident Ana Laureano said.
On Tuesday, heartbroken firefighters saluted as Fahy's remains left the hospital. The 17-year veteran was described as a "rising star" in the department and a dedicated family man who was married with three young children.
"Obviously the loss is tremendous for us, and I know everybody here feels terrible that his three children will have to grow up without him, but we're gonna do our best to make sure his memory lives on forever," Chief Mike Woods, FDNY Battalion 19, said.
At the Fahy home in Yonkers, a steady stream of mourners paid their respects.
"He was just a wonderful neighbor as you know him over the years with his children, his wife," neighbor Jackie Sutton said. "A pleasant, pleasant good man."
A donation page has been set for the Fahy family. If you'd like to donate, visit fdnyfoundation.org/donate and select the "Chief Michael J. Fahy Children's Educational Fund."
Mayor Bill de Blasio has ordered all city flags to be flown at half-staff in honor of Fahy.
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