Yorkville Police Detective Sgt. Larry Hilt said the vandals pulled the stem out of one tire each for about 70 Yorkville Community Unit School District 115 school buses overnight and deflated two tires on three or four buses, the Chicago Tribune reported Thursday.
Investigators said there were no overnight guards at the bus lot and the vandalism was discovered when drivers showed up for work at 5:30 a.m.
Asif Dada, a school district business manager, said several tire companies were called in to inflate or replace the tires.
Dada said all classes in the district were delayed by 1-2 hours.
Hilt said police had not made any arrests.