A Florida woman obsessed with the Columbine High School massacre and the Oklahoma City bombing was arrested after her parents discovered two dozen pipe bombs in her bedroom, the authorities said on Friday.

The woman, Michelle Kolts, 27, was charged with 24 counts of making a destructive device with intent to harm, Chad Chronister, the sheriff of Hillsborough County, said at a news conference.

Ms. Kolts had been on the radar of the authorities for more than a year, Sheriff Chronister said.

A printing company had contacted his department in 2018 because Ms. Kolts had ordered “several” manifestoes and “anarchist instructions,” the sheriff said, adding, “She became consumed with the Columbine and Oklahoma killings.”

In 1995, a homemade bomb planted outside a federal office building in Oklahoma City killed 168 people. The 1999 Columbine shooting, in which two gunmen killed 13 and wounded 21 in Littleton, Colo., has “infatuated” some young people and prompted copycat shootings across the country.