A former New York school teacher and his brother stockpiled bomb-making materials in their apartment and paid students to help them, authorities have claimed.

Police arrested brothers Christian Toro and Tyler Toro at their shared apartment on Thursday after uncovering more than 30 pounds of chemicals that could be used in explosives, New York City officials said at a press conference.

Both brothers have been charged with unlawful manufacture of a destructive device, and Christian has also been charged with distribution of explosive material to a minor. Both men have pleaded not guilty.

Police started investigating the brothers after Christian quit his job at a Harlem charter school in December, law enforcement and school officials said. His resignation came in the wake of a bomb threat to the school, for which one student was ultimately arrested.

According to a criminal complaint, Tyler returned his brother’s work laptop to the school shortly after he resigned. While cleaning out the laptop, a school employee allegedly found a book that included instructions for how to make a bomb.

Democracy Prep Public Schools, the charter school network for which Christian worked, said in a statement that a staff member "did a routine review of his laptop and was deeply disturbed by suspicious content".

"We immediately notified law enforcement of the content on Mr. Toro's laptop," spokesperson Rochelle Ritchie said. "We have been cooperating with the New York Police Department and the FBI since the beginning of their investigation and will continue to cooperate with authorities and provide any information we can."

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The complaint says Christian told agents he had downloaded the explosives book by accident, while researching the Boston Marathon bombing. He said he had never built a bomb and had only looked at the book’s table of contents.

But when agents interviewed students at the school, they discovered that Christian had paid at least two of them to break apart fireworks and store the gunpowder in containers, the complaint alleges.

Agents raided Christian and Tyler’s apartment on Thursday and found a glass jar containing explosive powder, a cardboard box containing firecrackers, and pounds of other chemicals that could be used to create explosives.

Agents also found a notecard scrawled with the words: “Under the full moon the small ones will know terror”. A diary that officials believe belonged to Tyler contained the passage: “We are twin Toros strike us now, we will return with nano thermite”.

Another passage included: "When you find out I threw away all evidence (of operation code name ‘Flash’) I could find in your room, I hope this doesn’t turn into a scene from Goodefallas.”

Officials did not release the name of the school where Christian taught, and said the investigation was ongoing.

Mayor Bill de Blasio said in a press conference that there was no ongoing threat to the city.

“From what we know at this point, the individuals involved have all been apprehended,” he said, adding: "Some good people stepped forward and that information that was crucial to law enforcement.”