A 17-year-old girl suffered third-degree burns to her head after a teenage boy set her hair on fire at their Brooklyn high school, police sources said Tuesday.

Authorities were called to Midwood High School at about 11 a.m. after the fire erupted. The 17-year-old boy was arrested at the school at 2839 Bedford Ave.

The girl suffered severe burns on her scalp, ear and neck and was rushed to a hospital.