The Associated Press reported at least 50 others were wounded in what is now being investigated as a terror attack.
The explosion happened on a train traveling between two stations near the city in northern Russia. Reports show all St. Petersburg subway stations have been shut down and passengers have been evacuated while investigators search for the cause of the deadly blast.
Russian President Vladimir Putin is expected to visit the city later today for talks with the Belarusian president.
The NYPD is also monitoring the situation and said it will make adjustments as needed to transit in New York City as more information becomes available.
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