HAVERHILL (CBS) – The windows of two school buses in Haverhill were shot out on Thursday.

Window shot out of Haverhill bus

At 11:30 a.m., a Head Start bus was hit near Marshland Street.

Then, at about 2:20 p.m., a high school bus was struck on Winter Street near Hale Street.

Children were on the buses at the time of the shootings. There were no injuries in either incident and no arrests have been made.

Police believe that a BB or pellet gun may have been used in the attacks.

Haverhill Superintendent Jim Scully says police officers will be very visible at school Friday and some will travel on the buses with the students.