俄罗斯警方确认地铁自杀炸弹袭击嫌疑人

Russian authorities have identified a suspect in Monday's deadly subway bombing in St. Petersburg, the Interfax news agency reports.

Interfax says police now believe it was a suicide bombing, and they identify the alleged bomber as a 23-year-old man from Central Asia.

The news agency quotes police who say he carried the bomb aboard the train in a backpack.

No one has claimed responsibility for the attack in Russia's second-largest city that killed at least 11, injured 50 and was powerful enough to blow a hole through the thick medal doors of a subway car.

A Russia TV station’s footage showed dead and wounded lying on a station platform, as horrified passengers rushed by, many of them covering their faces to avoid the thick smoke.

Police defused another bomb hidden inside a fire extinguisher at a second St. Petersburg station. The city's entire subway was shut down for much of Monday. Moscow took what it called "additional security measures" on its metro.

Officials in St. Petersburg have declared three days of mourning. Russian President Vladimir Putin happened to be in his hometown of St. Petersburg Monday for a meeting with Belarusian President Alexander Lukashenko. Putin brought flowers to the subway station, where a memorial of flowers and candles grows.

U.S. President Donald Trump calls the blast an "absolutely terrible thing," while a spokesman for U.N. Secretary-General Antonio Guterres said "those responsible for this appalling act must be held accountable."