Russian officials called for tighter controls on travel into Moscow (search) on Saturday, a day after a bomb explosion in a subway -- blamed on Chechen rebels -- killed 39 people and injured more than 100.
Police combed the twisted metal of the exploded subway car and questioned survivors in a search for clues to who staged the deadliest terrorist attack in the capital in years.
Based on a composite sketch of a suspect in the Friday morning attack, police detained two men for about three hours Saturday, police spokesman Kirill Mazurin was quoted as saying to Russian news agencies.
The sketch, released Saturday, was based on a videotape from the subway station nearest to the blast, showing a woman believed to be the bomber and her accomplice standing on the platform before boarding the train.
The bomb ripped through the subway car after it left the Avtozavodskaya station and headed for the city center, shattering windows throughout the train and leaving the car a hulk of twisted metal.
Shortly after the blast, bodies lay side-by-side on the seats, covered in soot. Of the 134 people wounded, 113 of them were still hospitalized Saturday.
Officials refrained from saying whether the blast was the work of a suicide bomber, though that was seen as the most likely scenario. "We have this information, but cannot say anything definite so far," deputy city prosecutor Vladimir Yudin told ITAR-Tass.
No one claimed responsibility for the attack, but President Vladimir Putin (search) accused Chechen separatists (search), calling the attack a failed attempt to sow discord before next month's presidential election.
Chechnya's chief mufti, or Muslim spiritual leader, condemned the blast. "There are no goals that can justify terrorism and the murder of peaceful civilians," Akhmad Shamayev (search) was quoted as saying by the news agency Interfax.
In Moscow, pressure on people from the southern Russian republic of Chechnya and others of North Caucasian appearance is likely to increase; those ethnic groups are already subject to close scrutiny in the capital and frequently stopped for document checks.
"All people who look suspicious must be sent away from Moscow," said Vladimir Zhirinovsky, leader of the ultranationalist Liberal Democratic Party.
Moscow Mayor Yuri Luzhkov said registration procedures in the capital would be "sharply, powerfully strengthened." Currently, Russian law calls for anyone coming to a city to register with local authorities within three days.
Dmitry Rogozin, a leading nationalist lawmaker with close connections to the Kremlin, called for introducing a state of emergency.
"The enemy is here, inside. This is an ethnic criminal community that evidently supports the terrorists coming to Moscow, owns property in Moscow and imposes its will on authorities," he was quoted as saying by Interfax.
After the bombing, security was intensified at railway stations and the capital's airports, news reports said. Police routinely stop people in the stations who appear to be Chechens or from the North Caucasus area, but crowds make thorough surveillance impossible.
The attack was the bloodiest in Moscow's subway, the world's busiest with an average 8.5 million riders a day. A bombing in a Moscow subway car in 1996 killed four people.
Hundreds of people were donating blood, reports said. A few flowers were left at the entrance to the Avtozavodskaya station.
Putin, who is expected to win the March 14 presidential elections handily, has built much of his strong image on a firm refusal to negotiate with the Chechen rebels whom Russia has been fighting for most of the past decade.
He linked the attack to Aslan Maskhadov, who was elected Chechen president after Russian forces withdrew in 1996 at the end of a disastrous 20-month war against separatist rebels.
Maskhadov's foreign envoy, Akhmed Zakayev, denied the Chechen leader was involved.
In December, a suicide bomber blew herself up outside the National Hotel across from Moscow's Red Square, killing at least five bystanders. Two suicide bombers blew themselves up at a Moscow rock concert last July, killing themselves and 14 other people. Five days later, an aborted suicide bomb attack at a Moscow restaurant killed a disposal expert who was trying to defuse it.
The deadliest terrorist bombings in Moscow occurred in 1999, when more than 200 people were killed in two apartment house blasts. Those explosions were among the events that prompted the Kremlin to launch the second military campaign in Chechnya.
In October 2002, 129 hostages died when Chechen rebels stormed a Moscow theater, almost all the victims died from the knockout gas that Russian forces pumped into the theater to end the siege.