"People are afraid it will happen again; they're trying not to go outside if they don't have to," said 20-year-old Yulia Kuzmina, a student. "We get a feeling that a war has started."
That is a worry that extends far beyond Volgograd.
Although there has been no claim of responsibility for the bombing of the city's main railway station and a trolleybus, suspicion falls strongly on Islamist insurgents, whose leader ordered his adherents this summer to do all they could to derail the Winter Olympics, which start Feb. 7 in the Russian resort city of Sochi.
Games organizers have introduced some of the most extensive identity checks and security measures ever seen at an international sporting event. But even if security at the Games is tight, many analysts suggest that the Volgograd bombings show how public transit in Sochi and sites away from the sports venues are vulnerable.
Police reinforcements and Interior Ministry troops have been sent into Volgograd, regional police official Andrei Pilipchuk was quoted as telling the Interfax news agency. He said more than 5,200 security forces are deployed in the city of 1 million, but did not say how much of an increase that was from normal levels.
Officers and security guards carefully searched the purses of young women entering a shopping center and waved metal detectors over both males and females.
The Cossacks guarding some bus stops added an unsettling note. Although these units are officially authorized volunteer patrols, they are descendants of the fierce horsemen who protected the czars and launched raids on Muslims in the Russian Caucasus, where the Islamist insurgency is now centered.
Volgograd authorities have canceled mass events for New Year's Eve, one of Russia's most popular holidays, and asked residents not to set off fireworks. In addition, all movie theaters have been closed until Thursday. In Moscow, festivities were to go ahead, but authorities said security would be increased.
President Vladimir Putin, in his New Year's Eve address to the nation, vowed that the fight against terrorists will continue "until their destruction is complete," Russian news agencies reported.
"What blasphemy. They did it right before the holiday," said Arkady Chernyavsky, a 73-year-old retiree. He also bristled at how the attacks stained the image of a city that prides itself for the tragic valor of the World War II Battle of Stalingrad, as the city then was called.
"This is supposed to be the city of heroes and things like this are taking place," Chernyavsky said.
Suicide bombings have rocked Russia for years, but the insurgents seeking to create an Islamic state have largely confined their attacks to the North Caucasus region in recent years. The blasts in Volgograd signaled that militants want to show their reach outside their native region. Volgograd is about 300 kilometers (200 miles) north of the Caucasus and about 690 kilometers (430 miles) northeast of Sochi.
China, host of the 2008 Summer Olympics, on Tuesday expressed confidence in the security of the Sochi Games.
"The competent authorities on our side have maintained close communication and cooperation with Russia in terms of the security work for the Winter Olympics. We believe that Russia is capable of ensuring security and hosting a successful Winter Olympics," Foreign Ministry spokeswoman Hua Chunying told reporters on Tuesday.
The United States would welcome "closer cooperation" with Russia on security preparations for the Winter Olympics, White House spokeswoman Caitlin Hayden said Monday.
Associated Press writer Jim Heintz in Moscow and researcher Zhao Liang in Beijing contributed to this report.
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