At least eight people were killed and more than ten others were injured as the roof of a swimming pool collapsed on Sunday in Chusovoi in the Urals region of Russia, the Interfax news agency reported.

But the Itar-Tass news agency quoted a source in the Perm department of the Federal Security Service as saying that the death toll in the swimming pool accident was four.

The source said the majority of victims were children and teenagers.

Two of the victims were children, and the death toll might increase as the effort to clear the debris continues, the headquarters of the rescue effort told Interfax.

The accident occurred at 2:30 p.m. local time (1130GMT), and about 30 people were in the swimming pool at the moment, said deputy regional prosecutor Alexander Belykh.

Eleven people have been sent to the hospital, while rescuers keep looking for survivors, Belykh said.

The swimming pool belonging to the Chusovoi metallurgical plant was built in the early 1990s. About 70 percent of the swimming pool (100 square meters) is now damaged, said the Itar-Tass.

The Perm regional prosecutor's office has opened an investigation into the accident.