• The materials were found hours after the fire was extinguished
  • No assembled device was found
  • The FBI and NYPD were investigating the incident

A fire that broke out in a Queens apartment on Tuesday took a curious turn when the landlord chanced upon chemicals that could be used to make an explosive device. The police have placed under observation "an emotionally distraught man" who was a resident of the house.

The fire was reported in the two-story building in the afternoon. Hours after it was put out by firefighters, the owner of the property found some suspicious-looking materials and immediately raised an alarm. Officers arrived at the scene and evacuated the house and other buildings in the area.

NYPD Deputy Commissioner of Intelligence and Counterterrorism John Miller said in a press conference that officers found bomb-making materials such as chemicals, manuals and books "about military explosive and booby traps."

"There was no assembled device found. At this point, the search will continue. We're going to want to go through the rest of that apartment. We're waiting to obtain a search warrant now that we've done the initial look to mitigate the immediate hazard, but I think the concern would be the individual chemicals that were found and what they could combine to make," Miller said in the press conference.

"The chemicals separately are what they are, but taken together they could assemble an explosive device," he said.

NBC New York quoted a senior law enforcement official as saying that at least 40 pounds of potassium nitrate were found at the property. There was no official confirmation regarding the same. The chemical is also used as a fertilizer and as an ingredient for fireworks.

Miller said a downstairs resident was taken to hospital for observation. He added that the person was known to the department and an investigation was on to find out "why he had these things." He was not charged.

"What we know is we had a fire, we had an emotionally distraught individual who had to be brought to the hospital, we had some chemicals in certain amounts that gave us concern about what they were for and what they could make together, and some written material that we're going to have to go over and figure out what all this means," Miller concluded.

The FBI and NYPD were investigating the incident.

tape police This image shows police tape around an apartment building. Photo: Ronald Martinez/Getty Images