Mourners laid flowers Wednesday at the gates of a Russian school where a day earlier a lone gunman killed nine people, mostly children, in one of the country's worst shooting incidents in recent history. 

Flags were flown at half-mast on official buildings Wednesday, an official day of mourning, while funerals were planned for some of the dead later in the day. 

Flowers were piled high outside School No. 175 in Kazan, the capital of the predominantly Muslim Russian republic of Tatarstan, where the shooting took place.  

"This is a huge and unexpected loss," Irina Krasnikova, 42, told AFP.

"We live in such a nice city. It's hard to believe this happened to us... It didn't happen to my children, but it is so painful, it's hard to speak".

The shooting left seven students and two adults dead, including a teacher, which TASS news agency identified as Elvira Ignatyeva who shielded students from the shooter.

A health ministry spokeswoman confirmed to the RIA Novosti news agency Wednesday that 18 children were in hospital, including eight with gunshot wounds and two in critical condition.

The state-run TASS news agency cited a source as saying funerals would be held Wednesday, while RIA reported the remains of the victims were being returned to families.

The shooting shook Russia and spurred President Vladimir Putin to order a review of gun laws.

In the wake of the attack, the speaker of Russia's lower house of parliament, Vyacheslav Volodin called on lawmakers to debate a bill tightening controls over gun licences next week.

Russia has relatively few school shootings due to normally tight security in education facilities. 

Buying firearms legally is also not easy, although it is possible to register hunting rifles.

The gunman was identified as 19-year-old Ilnaz Galyaviev from Tatarstan who had been expelled from a local technical college over a poor academic record.