"We heard a clap, then saw smoke, and it smelled of plastic and burnt insulating tape. We thought that something in the train had broken," RIA Novosti was told by a man who stayed in the last but one car of the train where the explosion resounded.
He said that "the train immediately stopped, and the engine-driver announced that the supply of electricity was discontinued and people should leave the cars".
According to him, people covered a distance of approximately 100 metres to Avtozavodskaya metro station by themselves and went out onto the surface.
He said that the first police cars and ambulances had already been coming by that time.
The explosion resounded at 8.45 a.m. Moscow time on Zamoskvoretskaya line during the movement from Avtozavodskaya station to Paveletskaya, towards the centre.
As Russia's Deputy Minister of the Interior Alexander Chekalin said, the explosion occurred near the first door of the train's second car.
By Chekalin's data, thirty people died and thirty were injured and rushed to hospital as a result of the explosion.