MOSCOW - A bomb tore through a crowded underground walkway in central Moscow on Tuesday, killing at least seven people and sending wounded pedestrians staggering out, their clothes singed, tattered and soaked in blood.
Suspicion for the bombing immediately fell on Chechen rebels, and there were fears of a renewed terrorist onslaught in the Russian capital.
The blast shook the crowded walkway filled with kiosks in Pushkin Square during evening rush hour. Pedestrians, many with limbs bleeding, stumbled up the steps from the passageway to the surface, shouting and coughing, while others ran for cover.
Rescuers later dragged burned corpses out of the tunnel past charred heaps of kiosks.
Emergencies Minister Sergei Shoigu said seven people were killed and 53 injured in the blast. President Vladimir Putin ordered police on alert around the country.
''We should stop speaking about freedom of movement ... We should realize we are living in the capital of a warring country,'' Alexander Muzikantsky, a Moscow city official, told ORT television.
The Interior Ministry released descriptions of two suspects, both men in their late 20s with dark skin and ''apparently from the Caucasus region,'' Russian television reports said. Chechnya is in the Caucasus.
Police said there was no immediate claim of responsibility for the blast. Moscow Mayor Yuri Luzhkov said city prosecutors were treating it as a terrorist attack and that Chechens could be to blame. Chechen rebels were blamed for a series of apartment bombings last fall that killed around 300 people and in part prompted the Kremlin to launch the current war in Chechnya.
Maria Korzhenikova, a 19-year-old saleswoman who was working in one of the kiosks that lined the passageway when Tuesday's blast hit, wandered around dazed.
''I thought if I don't get out now I'll die,'' she said. ''I was sitting reading a book ... then the lights went out. The door I was supposed to go through was jammed. It was pitch dark, I climbed through a window.''
She had a scrape on her shoulder, her sleeve was bloody and her face was covered in dust. She was barefoot because she had taken off her shoes for relief from the summer heat before the explosion.
Pushkin Square is one of the busiest junctures in Moscow, adjoining two major streets and three subway stations less than a half mile from the Kremlin and a few hundred meters from the Moscow mayor's office.
People outside the walkway when the bomb exploded said the blast barely disturbed them and sounded like a minor car accident. Only as blood-soaked people began stumbling out was it clear what happened, said Galina Romanova, who sells ice cream in the area.
Police and security agents flooded the square, pushing frightened onlookers back toward a McDonald's restaurant as smoke gushed from the passageway.
A second bomb was found and defused near the scene, the Interfax news agency said. Officials would not confirm the report.
Putin, who gained popularity partly through his tough response to last year's bombings and handling of the Chechnya war, called an emergency session of his top law enforcement officials Tuesday.
Last year's blasts put pressure on the government to show it was increasing security, and residents in Moscow and other big cities set up neighborhood patrols to guard homes around the clock. Human rights activists said police responded to the earlier bombings by indiscriminately detaining and harassing minorities.
The Kremlin blamed Chechen rebels for those bombings - two of which were in Moscow - and sent troops into Chechnya a few weeks later. The Chechens denied responsibility.
Tuesday's blast came two days after Russian security forces had been on alert in case of possible attacks by Chechen separatists to mark the Aug. 6, 1996 anniversary of the rebels' capture of the Chechen capital of Grozny during the first Chechen war.
Earlier Tuesday, security agents seized large batches of explosives during raids in Moscow and the southern city of Ryazan, the Interior Ministry said, according to the ITAR-Tass news agency. The ministry said the explosives were intended for terrorist acts by Chechen separatists.
The U.S. State Department and German Chancellor Gerhardt Schroeder expressed condolences for the victims of Tuesday's explosion.