Two Colorado girls, 16, detained over high school threat

By Keith Coffman

DENVER (Reuters) - Two 16-year-old girls in Colorado have been detained on suspicion of conspiracy to commit first-degree murder following a threat to students and staff at a Denver-area high school, authorities said on Tuesday.

News of the development at Mountain Vista High School emerged as authorities nationwide grapple with how to handle such threats, and Los Angeles shut more than 1,000 public schools over a threatened gun and bomb attack.

Sergeant Lori Bronner, spokeswoman for the Douglas County Sheriff's Office in Colorado, said police became aware of the suspected plot on Saturday.

She said it was unrelated to the emailed threat received more recently by school districts in Los Angeles and New York.

Both the girls attend Mountain Vista, Bronner said, and investigators acted immediately to apprehend them after learning of a "credible threat" to harm staff and students at the school in Denver's southern suburb of Highlands Ranch.

Citing the investigation, Bronner declined to elaborate, but said there was no specific time frame during which the alleged plot was to take place. Schools in Douglas County, including Mountain Vista, were closed on Tuesday because of snow.

The school district's superintendent, Liz Fagen, wrote to parents saying she felt compelled to get in touch with them because of "the nature and gravity" of the situation.

"We want you to know that many of the safety systems we have in place worked well ... and it was through these systems, including our partnerships with law enforcement and our families, that this threat was successfully disrupted," Fagen said in her letter, which the district posted online.

Colorado has been the scene of at least four school shootings in recent years, the deadliest being the 1999 attack on Columbine High School outside Denver in which two students fatally shot 12 classmates and a teacher before committing suicide.

"We take these types of threats extremely seriously and will take all efforts necessary to ensure the safety of our schools, students, and teachers," Douglas County Sheriff Tony Spurlock said in a statement.

(Reporting by Keith Coffman; Editing by Daniel Wallis and Peter Cooney)