Const. Ian MacDonald says the fires were set over a 48-hour period on Monday and Tuesday.
A wooden bench, dumpsters and garbage cans were set alight either in the early morning or early evening hours.
While the fires were all small, police say they all had the potential to cause greater damage because they were near other structures.
The teens, aged 13, 14 and 15, were taken into custody on Wednesday.
MacDonald says all three face arson charges.