Three fires at a Whangarei school are thought to have been deliberately lit.

Two of the fires were discovered by cleaners at Mania View Primary School on Tuesday and another was found yesterday morning.

Whangarei police spokesperson Sarah Kennett says CCTV footage from the school shows a group of two men and three women, aged in their 20s, who Police believe could be involved.

Apart from smoke residue, none of the fires caused significant damage.