Three teenage girls from south Essex have been arrested on suspicion of arson.
It follows a number of suspicious fires at Southend High School for Girls.
The students - two aged 15, and one aged 14, from the Thorpe Bay and Hadleigh areas - have been questioned by officers from Shoebury police station.
Essex Police said the girls were questioned about the fire at the Southend High School for Girls in Southchurch Boulevard on 1 May.
The girls have been released on police bail until 27 August, pending further inquiries.