N'DJAMENA (AFP) - Police in Chad have arrested nine people, including five suspected rapists, after photographs of a girl allegedly brutally gang-raped spread on social media, the public prosecutor in the capital N'Djamena said Tuesday.

"Five rapists and their four accomplices have been detained," Louapambe Mahouli Bruno told the press.

He also said a young man was killed when riot police violently shut down a protest by hundreds of young Chadians in N'Djamena on Monday.

The protesters had said a girl named as Zouhoura was kidnapped last weekend and gang-raped by five young men from the families of senior officers.

The men then allegedly posted a video online showing the victim in tears.

The video has since been removed.

On Monday morning, pupils from Zouhoura's high school and other protesters gathered outside the girl's home and marched to the court to demand compensation for her.

Singing the national anthem, they waved banners that read "Justice for Zouhoura" and "We are all Zouhoura, our dignity is being denied".

In a statement, Chadian President Idriss Deby Itno lashed the rape as a "barbaric, vile and unmentionable act" and swore "justice will be done."