LAFAYETTE, Colo. - Lafayette police say a teacher found a pipe bomb inside Centaurus High School in Lafayette on Monday morning, prompting evacuation of the school.
Initial reports said the device was found outside the school.
During an evening news briefing, Lafayette Police Cmdr. Gene McCausey said the teacher found the pipe bomb in a paper bag inside the school at about 8:30 a.m. and carried it outside.
If the device had exploded near people, they could have been injured, McCausey said. There was a battery attached to the device, but McCausey would not say whether it could have been remotely detonated.
The Boulder County Bomb Squad used a robot to remove the device from the school around 11:30 a.m. It was driven up a road into an empty dirt construction lot in Louisville. An excavation crew dug a hole for the detonation and the item was exploded at about 12:30 p.m.
It made a small "whoof" sound when it was detonated, said 7NEWS photojournalist James Dougherty.
Several people who were in the area watched the detonation and appeared disappointed, telling police officers, "You made us stand around for that?"
Agents from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives have joined the investigation.
McCausey said investigators have identified persons of interest and were interviewing people throughout the day.
"Unfortunately, these are the times we live in," McCausey said. "We're going to do our best to keep our kids safe."
Meanwhile, officials said classes will resume at the school on Tuesday morning.
Because of the evacuations, several students and staff members were forced to leave their vehicles parked in the school lot on Monday. Police let students come to pick up their cars from the lot about 9:30 p.m. Monday.
Earlier in the afternoon, police were using bomb-sniffing dogs to search each vehicle. Because of the hot weather, the dogs were tiring quickly, McCausey said, so additional bomb-detecting dogs were brought in from agencies around the metro area.
The students at Centaurus were evacuated to a field at nearby Ryan Elementary initially but were later released for the day and all classes were canceled.
The Boulder Valley School District sent a note around 11 a.m. to parents and faculty member informing them of the investigation and evacuation.
The district sent another note around 3 p.m., letting parents know that the school building and parking lot will remain closed Monday night, with no access to the cars in the parking lot. Track and field practice was canceled, girls soccer practice was moved to Peak to Peak Charter School and girls lacrosse was moved to Casey Middle School.
"I didn't expect it to be the real deal. I thought it was like something, like minor," said student Sara Nygaard. "I don't know how to feel about it. I'm a little confused on why?"
Sara's mother, Kathleen Nygaard, said: "You can't hide from it. But at the same time, you have to be aware, careful and cautious."