The victims include mainly women and children, according to local emergency ministry official Anatoly Shinakov.
He told ITAR-TASS news agency that seven bodies had already been recovered.
But he warned there could be more bodies under the 100 square-metre roof, which collapsed at the municipal pool in Chusovoi, a town near the city of Perm in the Ural mountains.
He said up to 30 people could have been in the pool at the time of the accident.
Earlier, a spokeswoman for the Perm provincial governor's office, Anna Klimova, said the toll from the accident had reached nine.
Rescuers have continued to work at the scene of the reinforced concrete building and have managed to remove over half of the collapsed roof, Mr Shinakov said.
Officials did not immediately give a reason for the collapse.
An abrupt change in the weather which brought heavy snowfalls is thought to be a possibility.
Local prosecutors have opened a criminal investigation.
In February 2004, 28 people died and almost 200 were hurt in a collapse at a water park in Moscow.
The design of the building was blamed.