A car has exploded outside a hotel near Moscow`s Red Square on Tuesday morning, killing at least five people, police have said.It was not clear whether the blast was due to a terrorist act or a business dispute that had turned violent, police said.The ITAR-Tass news agency reported that the explosion had been caused by a female suicide bomber, and that an undetonated explosive had been found on the bomber`s body.The Interfax news agency said that a law enforcement official on the site said there may have been two suicide bombers, and that moments before the blast they asked passers-by where the lower house of parliament, the State Duma, was located.