Moscow - At least 10 people were killed in an explosion at the Senaya Ploshad station on the blue subway line in St. Petersburg, the TASS news agency reported, but there was no official confirmation.

The channel Rossia 24 showed images of one of the doors of a car that exploded in the mentioned station and photos of at least two people lying on the ground and several ambulances in the outskirts of the referred underground station.

In the Technological Institute station, also on the blue line, a strong smoke was reported, said Rossia channel 24.

Authorities were reportedly aware of or warned of the possibility of terrorist attacks, as they located some suspicious objects shortly before the blast, but according to specialists, they could also be distracting.

Shortly after, Ploshad Vastania stations 1 and 2 were closed.

Rossia 24 indicated that the convoys do not stop at least seven metro stations and three of them are carried out checks.

President Vladimir Putin, attending a meeting in St. Petersburg with his Belarusian counterpart Alexander Lukashenko, was briefed on the detonation, said Kremlin spokesman Dmitri Peskov.