PRESCOTT VALLEY, Ariz. — Authorities in Prescott Valley said 66 buses were damaged in what investigators believe could have been part of a senior prank. School officials originally thought 83 buses were vandalized.

Prescott Valley police said officers were called to the Humboldt Unified School District bus barn at about 4:30 a.m. Monday after employees discovered damage to the buses.

“We have made all the necessary repairs to our buses. And the district was able to provide all the mid-day and afternoon runs as scheduled," said Dan Streeter, assistant superintendent.

The repairs have cost the district $3,500 dollars so far.  District officials came up with alternate transportation to get several hundred children to school and were forced to cancel previously scheduled field trips. The district is reviewing video and working with the police to catch the vandals.  Buses are scheduled to be back on their normal routes tomorrow.

Updated at 5/11/2015 at 3:53 p.m.