A police vehicle is seen in front of the Boulder High School after police responded to an unconfirmed report of an active shooter in Boulder, Colorado, U.S., on Wednesday.
DENVER--A spate of anonymous telephone calls warning of attacks on public schools sparked evacuations and lockdowns in at least a dozen Colorado school districts on Wednesday, but the measures were lifted after police determined the threats were unfounded.
The security scare began shortly before 9 a.m. when a man called emergency-911 claiming he was about to enter Boulder High School armed with semi-automatic weapons, according to Maris Herold, police chief for the city of Boulder. The call prompted police cruisers, fire trucks and ambulances to rush to the school, normally attended by some 2,170 students, as police issued a shelter-in-place order for the campus, Herold told reporters.
"I have listened to the 911 call. It is very scary," she said at a news conference, adding that sounds resembling gunfire could be heard in the background of the call.
A sweep of the school uncovered no evidence of a gunman or victims, Herold said. About 200 students and staff were evacuated following the report, she said, explaining that classes at Boulder High start on a delayed schedule on Wednesdays.
The chief declined to characterize the situation as a hoax, saying she needed to assess the matter further with FBI agents involved in a broader investigation of similar incidents across Colorado. Threats of violence that never materialized were known to have sparked security precautions in at least 17 school districts or individual schools statewide, according to a Reuters' tally.
The FBI in Denver said it was aware of numerous threats made to organizations and institutions across the state on Wednesday, although it had no information to indicate a specific and credible threat.
According to the Alamosa School District, 230 miles (370 km) south of Boulder, someone called early Wednesday morning saying an armed individual had entered a middle school there, triggering a lockdown that was lifted soon after.
Brighton High School, about 25 miles east of Boulder, had also been under lockdown after police in that city received a phone threat about Ortega Middle School. The Brighton Police Department said in a tweet that officers have found no credible threat to students or the surrounding community and that lockdown had been lifted.
Schools in Canon City and Aspen were also placed on lockdown after receiving threats on Wednesday morning. Those lockdowns have since been lifted, school officials said.
