Witnesses told police that the youth appeared to be around 15 or 16 years old. He was seen knocking on several doors in the school and when one 17-year-old girl opened her bedroom door he pushed his way in and tried to photograph her.
After a brief scuffle she managed to push him out of her room but he was then able to get into another 17-year-old girl's room where he exposed himself to her.
She ran from her room but was pursued by the youth, who managed to rip off her t-shirt. After a struggle she was able to run into another room and lock the door.
Police said the teenage boy was in the school between 3:50 and 5:20am and then managed to run away without being caught.
The girls said he was between 160 and 165 cm tall and that he wore a bright blue and turquoise hooded sweater, dark blue jeans and a hooded winter jacket. They did not hear him speak, and said they had never seen him before.
Police said that none of the girls were hurt and it is unclear how the intruder managed to get into the school.