(Adds no other devices found, additional details)
By Laura Zuckerman
April 22 (Reuters) - Nearly 800 students and teachers were evacuated from a suburban Utah elementary school on Monday after a custodian found a pipe bomb on the roof, a school official said.
No one was injured and police detonated the bomb using a high-pressure water cannon at Mountain View Elementary School in Layton, about 25 miles (40 km) north of Salt Lake City, said school district spokesman Christopher Williams.
The custodian removed the bomb from the roof and then alerted the school principal, who called police, said Williams.
"Why he did that and where he took it, we're not sure. He put himself in a dangerous situation," Williams said of the custodian.
No threats had been received at Mountain View Elementary School or any of the other 85 schools in the district, and no bombs have previously been found on district property, Williams said.
A different custodian had been on the roof on Friday to retrieve a ball and had not seen any suspicious devices in the same area where the bomb was found on Monday, Williams said.
"That doesn't mean it (the pipe bomb) wasn't up there. As to who may have placed it up there, we have no idea at this point," he said.
The incident was being handled by the Layton police and fire departments and the Davis County Sheriff's Office bomb squad, which did not immediately return calls seeking comment.
Bomb-sniffing dogs from nearby Hill Air Force Base searched the school on Monday for additional devices but none were found. Maintenance workers at all the district's schools were asked to examine roofs as a precautionary measure, Williams said.
"We drill a lot for fire, intruders, disasters. That means when there's a real situation like today, everything goes smoothly. Under the circumstances, things went as well as they could," he said. (Reporting by Laura Zuckerman in Salmon, Idaho; Additional reporting by Dan Whitcomb in Los Angeles; Editing by Cynthia Johnston, Dale Hudson and Lisa Shumaker)