A rash of car robberies in suburban Baltimore led police to uncover an alleged school shooting and bombing plot just two days before the planned spree. Sash Alexander Nemphos, 16, was charged Monday as an adult after Baltimore County cops said they found weapons in his Monkton home, including a handgun and materials to make homemade explosives, reported NBC affiliate WBAL. Detectives say they nabbed Nemphos after investigating a series of nearby car break-ins on Saturday and getting tipped off by neighbors.

Upon questioning at his home, police said, Nemphos confessed to planning to kill people at George Washington Carver Center for the Arts and Technology, where he is a sophomore. He had taken a handgun with him on Friday stashed inside of his backpack, but decided to put off an attack until Monday, police added.

Investigators say Nemphos revealed the weapons to them on Saturday but didn’t provide a motive for the plot. He remains held without bail and was initially taken for a mental health evaluation.

About an hour-and-a-half north in suburban Philadelphia, another suspected school shooting was thwarted Monday when a 17-year-old was arrested in Radnor Township, police said. The unnamed senior at Radnor High School detailed in a notebook that she was influenced by the 1999 Columbine High School massacre and wanted to become the first female mass murderer, police said. The girl was arrested and will be charged as a juvenile for making terroristic threats, according to NBC Philadelphia.

Sash Alexander Nemphos, the 16-year-old boy charged as a juvenile after several explosive devices and a gun were found in his home. Baltimore County Police

SOCIAL

#BCoPD has disrupted school shooting plans by 16-yr-old Carver student. The boy is charged as a juvenile. http://t.co/peu0tMyF1y ^EA — BACO Public Safety (@BACOPoliceFire) November 3, 2014

#BCoPD Chief : the officer in this case did an exceptional job .... we intervened in what could have been an extremely serious situation — BACO Public Safety (@BACOPoliceFire) November 3, 2014

— Erik Ortiz