The teen gunman who shot himself dead after critically wounding a fellow student at their suburban Denver high school legally purchased the shotgun and ammunition he used in Friday's rampage at Arapahoe High School, according to Sheriff Grayson Robinson.
A vigil being held in Arapahoe for 18-year-old Claire Davis, who was critically injured in the school shooting.
The attack by Karl Pierson, 18, lasted less than a minute and a half, the sheriff said.
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Explosives experts were called to the nuclear reprocessing site in Cumbria, to help deal with chemical substances.
The arrests were made on suspicion of producing and disseminating pedophilia content on the internet, the country's Justice Ministry said.
The A4-sized sketch originally went for £75 when it was first sold.