Authorities in Tennessee say a 15-year-old high school student set his teacher's hair and clothes on fire during class earlier this week.

Gabriela Peñalba, a science teacher at West High School in Knoxville, reportedly had her back to the classroom when the teen snuck up behind her and ignited her hair and shirt with a lighter.

Students rushed to the 23-year-old teacher's aid, helping her extinguish the blaze.

Exploiting the commotion, the student tossed the lighter out of a nearby window and fled, but was soon caught by school resource officers.

The unidentified suspect reportedly confessed to the crime in a police interview, but his motive remains unclear.

He was subsequently charged with aggravated assault and evading arrest and transported to a juvenile detention facility.

Luckily, Peñalba did not suffer serious burns — a result credited to the quick response of her students.

[photos via Facebook]