NEW YORK (CBSNewYork) — Two twin brothers from the Bronx, one of them a former teacher, were arrested by federal authorities Thursday in an alleged bomb-making plot.

Christian and Tyler Toro, both 28, were arrested Thursday, police said.

As CBS2’s Jessica Layton reported, the NYPD and FBI would not say what exactly the Toro brothers had planned. But the evidence was enough to land them federal charges.

READ THE COMPLAINT AGAINST THE TORO BROTHERS

At a news conference Thursday evening, Mayor Bill de Blasio, NYPD Commissioner James O’Neill and other officials said tips from staffers at the school were crucial to cracking the case.

“This is a moment to remind all New Yorkers, to remind everyone, that the idea that if you see something, you say something is more pertinent than ever,” de Blasio said. “We get daily reminders of the threats arrayed against us.”

De Blasio also called the arrests “another example of the very close working relationship between the NYPD and the FBI; the City of New York and our federal partners.”

De Blasio and O’Neill said while only preliminary information could be released Thursday night, it was believed that all those involved in the bomb-making plot had been apprehended and there was no threat to New York City.

“We have no indication that there is a continued threat posed by these individuals, but we do not stop and investigation just because somebody is in custody,” said FBI Assistant Director in Charge William Sweeney.

A federal complaint filed Thursday said on Dec. 4, a bomb threat was called into a high school in Harlem and a student was arrested.

The NYPD Intelligence Bureau launched an investigation and interviewed students, teachers, and others at the school, NYPD Deputy Commissioner of Intelligence and Counter-terrorism John Miller said.

On Jan. 10, Christian Toro – a teacher at the school – abruptly resigned, the complaint said. The teacher’s resignation caused the investigation to continue, and the FBI and NYPD Join Terrorism Task Force got involved, Miller said.

Afterward, Christian and Tyler Toro returned the laptop that the school had provided to the teacher, and a technical specialist found a copy on the laptop of a book called “The Explosives Book” that provides instruction for making explosives, the complaint said.

On Feb. 8, FBI agents interviewed Christian Toro at an apartment on Matthews Avenue in the Pelham Parkway section of the Bronx, where the brothers live with a female relative, the complaint said. In the interview, Christian Toro said he had not downloaded “The Explosives Book” to the laptop, but said he had come across it while researching the 2013 Boston Marathon bombings, the complaint said.

Christian Toro said he had never built a bomb and only looked at the book’s table of contents, the complaint said.

On Wednesday, FBI agents interviewed multiple students at the school who said they had visited the Toros’ apartment and that Christian Toro would pay them about $50 per hour to break apart fireworks and store the powder that came out in containers, the complaint said.

Based on interviews, it appeared that the students visited the apartment between October 2017 and early January 2018. Miller said at least two students were involved in harvesting the black powder from the fireworks.

The complaint said on Thursday, FBI agents executed a search warrant and found the following substances in a bedroom closet:

• About 20 pounds of iron oxide;

• About 5 pounds of aluminum powder;

• About 5 pounds of potassium nitrate;

• About 2 pounds of confectioner’s sugar.

A glass jar containing a black powdery substance that was found to be an explosive was also found on a shelf in the closet, while a substance believed to be thermite – made from iron oxide and aluminum powder – was found in a plastic container in another closet, the complaint said.

A bag containing metal spheres of various sizes was also found in the second closet, the complaint said.

All of substances found in the closets can be used in making bombs, the complaint said.

Agents also found a diary on a kitchen able with handwritten pages, the complaint said. The diary said if lost, it should be returned to Christopher Toro, and it said among other things:

“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.”

“We are twin Toros strike us now, we will return the nano thermite.”

“Christian arrested.”

“If you’re registered as a sex offender, things will be difficult. But I am here 100% living, buying weapons. Whatever we need.”

Toro had been arrested by the NYPD on Jan. 31 and was charged, among other things, of the rape of a victim under 17, according to the complaint. O’Neill declined to provide details.

Also found was a yellow backpack which contained a purple index card with the handwritten message, “Under the full moon the small ones will know terror,” the complaint said. The backpack was found to belong to Christian Toro, the complaint said.

Democracy Prep Charter High School in Harlem, where Toro was a teacher, issued the following statement:

“Mr. Toro had worked for Democracy Prep Public Schools since August 2016. He did not return to work after December 21, 2017 and officially resigned from Harlem Prep High School January 9, 2018. After he resigned, Democracy Prep 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. 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. Any further questions should be directed to the NYPD and the FBI as this is an ongoing investigation.”

Police had no prior indication that the brothers might be up to no good.

“Neither of these two individuals were on our radar before this, nor did they have any criminal background that preceded this investigation,” Miller said.

And it seems they weren’t on the radar of their neighbors either.

“They seemed like good guys,” said neighbor Raymond Deldiolai.

“I’m surprised this happened,” said neighbor Elsie Cole. “I’ve never had this experience, especially this area. The people are great. It’s a working neighborhood. I’m shocked, I’m really shocked.”

Both defendants were charged in U.S. District Court with unlawful manufacture of a destructive device and distribution of explosive materials to a minor.

The brothers both pleaded not guilty in court Thursday night. Police said the students who were helping them store powder were not arrested.