ST PETERSBURG, Russia (Reuters) - An explosive device killed two people in a St Petersburg apartment building but officials on Friday denied any link with recent bomb attacks that have killed almost 300 people in Moscow and other cities. The device went off outside a door to one of the apartments, killing two people and injuring two people, including a child. „This explosion is in no way connected with the series of terrorist acts in other citites and is most likely the result of a criminal settling of accounts,“ said the deputy head of the St Petersburg police department, Nikolai Yegorov. Yegorov said that none of the residents of the apartment block seemed to have criminal links and said that the device might have been placed there by mistake. An Emergencies Ministry duty officer in St Petersburg had first said the blast, which occurred at 11:30 p.m. (1930 GMT), on Thursday had been caused by a gas leak. A police expert said on Friday that the blast was equivalent to almost 5 kg (11 lb) of TNT. It was much smaller in scale and effect than four bomb explosions in Russia since August 31, which have killed almost 300 people and caused near panic across Russia. A St Petersburg Emergencies Ministry official said the explosive device went off at the doors of an apartment on the seventh floor, badly damaging a stairway between the sixth and the eighth floor and one inner wall. The fire also damaged two apartments on the sixth and the eighth floor. It was put out within an hour. The building, near the city port area, appeared undamaged from the outside, with slightly smoked walls and burnt-out windows on the damaged floors. Residents were evacuated. Maria Gorelova, who lives on the second floor, said the husband and wife, who were killed in the flat, were „people like you and me, nothing special.“