Meanwhile, security measures have been stepped up in the region. Both public transport and private cars are being checked.

“It’s rather a complicated procedure when we speak about the prevention of terrorist attacks in public transport. It’s impossible to search every bus passenger. We also cannot install special equipment for explosive detection as they do in airports, or employ sniffer dogs,” Arkady Baskaev, State Duma Deputy, says.

The U.S.-backed station Radio Liberty has received a video tape on which Doku Umarov urges a “Holy War” not only against Russia, the U.S., the UK and Israel, but also against all states.

The script of the tape was sent to the radio station earlier last month.

On Thursday, Togliatti residents held a rally to commemorate those killed. People gathered in the city’s centre to lay flowers and light candles. Some brought poems that they'd written.

According to acting deputy city mayor Vladimir Ivanov, relatives of those killed will get $US 12,000 compensation, and between $US 4,000 and 8,000 will be paid to those injured.

In addition, Russia's leading asset management company – RENOVA Group of Companies – has donated 2.5 million roubles, or $US 100,000, to the families of those killed. The company has also agreed to cover part of the medical expenses of those injured in the tragedy.

“I’d say our motivation is human and Christian. At some point each company realises that they should provide not just a charity programme, but also direct assistance. It makes no sense to give away money on the streets. It's essential to have criteria. For us, firstly, it’s tragic situations. We help people when they are without hope and in need of assistance, those who have no time or resources to go to the courts. Secondly, we try to help those regions where RENOVA businesses are located,” Andrey Strokh, Spokesman for RENOVA Group of Companies, says.