A Florida teenager is dead from an apparent self-inflicted gunshot sound following a nearly 24-hour manhunt.

Sol Pais flew into Denver International Airport Monday night. She then bought a pump-action shotgun from a gun shop in Littleton near Columbine.

Updated at 5:20 p.m. ET

The FBI says an "armed and dangerous" 18-year-old white woman obsessed with Columbine is dead from an apparent self-inflicted gunshot wound. Because of warnings about the Florida woman named Sol Pais, more than a dozen school districts in Colorado were closed Wednesday.

The 20th anniversary of the Columbine High School shootings is Saturday.

After years of tension over expanded oil and gas drilling, including a deadly explosion that galvanized critics, Colorado is moving to tighten regulations on the booming industry. In a sweeping overhaul the governor is expected to sign, regulators will now have to consider public health, safety and the environment in decisions about permitting and local land use.

The state must still hammer out the details of how to implement the new law over the next year. But the impending changes are already fueling hope for some, and fear for others.