At least 37 people have been killed by two explosions which hit the Moscow Metro¹ system at the peak of the morning rush hour, Russian officials have said.

俄罗斯官员称，莫斯科地铁系统在上午上班高峰时刻发生两起爆炸事故，造成至少37人丧生。

At least 37 people are reported killed in two explosions on the Metro system in Moscow, officials say.

The first blast went off（爆炸，离去） in the central Lubyanka station at 0756 (0356 GMT). Police said the dead included 14 people inside a train and 11 on the platform.

The second explosion occurred about 40 minutes later at the Park Kultury station, where 12 people were killed.

Authorities in the capital have declared it a "terrorist" incident.

The BBC's Rupert Wingfield Hayes in Moscow says no-one has yet claimed responsibility, but the explosions do appear to have been co-ordinated.

Moscow's metro is one of the most-used underground railways in the world, carrying some 5.5m passengers a day, our correspondent says.

Suspicion is likely to fall on groups in the troubled（动乱的，混乱的） North Caucasus（高加索） region, where the authorities are fighting Islamist militants², he adds.

'Suicide bombings'

Emergency services ministry³ spokeswoman Irina Andrianova said the first explosion tore through the second carriage of a train as it stood at the Lubyanka station, close to the headquarters of Russian Federal Security Service (FSB).

She said people both inside the carriage and on the platform had been killed.

"There was no fire. Rescuers of the Moscow emergencies department and firefighters are now working at the site," she added.

The second blast, at Park Kultury, came at 0838 (0438 GMT).

Prosecutors⁴ in the capital told the Russian Interfax news agency that initial reports indicated both of the explosions were suicide bombings.

Russian forces have scored a series of successes against militants in recent weeks. In February, at least 20 insurgents⁵ were reportedly killed in an operation by Russian security forces in Ingushetia（印古什） .

There was a major attack on the Moscow Metro in February 2004, when at least 39 people were killed by a bomb on a packed train as it approached the Paveletskaya Metro station.

Six months later, a suicide bomber⁶ blew herself up outside a station, killing⁷ 10 people. Both attacks were blamed on Chechen rebels, who had targeted the capital in the past.