A New York teen accused of scrawling a swastika inside his high school was allegedly found with homemade explosives at home, leading police to arrest both the 15-year-old and his father.

Nassau County police said officers went to the Syosset home on Wednesday after the teen allegedly drew a swastika and racial slurs at Syosset High School. Once there, investigators discovered chemicals that had allegedly been combined to make explosive materials.

Authorities said they found acids, oxidizers, bomb-making tools, and nitroglycerin, an extremely unstable explosive. Police shut down the residential street for hours while the bomb squad handled the materials. Officials said the substances were too dangerous to move and were destroyed on site in controlled detonations.

The teen’s father, 48-year-old Francisco Sanles, was also arrested. Prosecutors allege he used his credit cards to buy some or all of the chemicals for his son on multiple occasions. The teen reportedly told investigators his father believed the materials were being used to “build rockets.”

Sanles was charged with criminal possession of a weapon, criminal facilitation, endangering the welfare of a child, and reckless endangerment. He pleaded not guilty Thursday and was held on $100,000 bail. His attorney said he “vehemently denies” the allegations.

The teen, whose name was withheld because of his age, was charged with criminal possession of a weapon, criminal mischief, aggravated harassment, and making graffiti. He is expected to appear in family court.

The Syosset school district told families that swastikas and racial epithets had been found above urinals at the high school and said the student would face “serious consequences” under the district’s code of conduct.

“Antisemitism and hate speech have no place in our communities or in our schools,” the district said.