The bomb explosion has killed businessman and injured 4 other people at Moscow center, officials said.
The explosive device, placed in a parked motorcycle, went off shortly before noon with the force of some 500 grams (17 ounces) of TNT, the Prosecutor General's Office said in a statement.
The blast occurred outside the office of a private company and killed the company's director, the statement said. Four people were hospitalized with injuries of varying severity.
Deputy Moscow Prosecutor Alexei Grigoryev said the blast could have been the result of a business dispute, suggesting the victim may have been targeted in a contract killing. He said there was no evidence of terrorist intentions.
An Internet business-information site indicated the company, Blagvest, is involved in trade. There was no answer at the phone numbers listed.
Contract killings are common in Russia.
World's most powerful nuclear submarines, Arkhangelsk and Severstal, are to be dismantled after 2020 - their further exploitation is unprofitable
The United States' Head of Diplomacy, or Secretary of State, is an anachronistic, incompetent, meddling, intrusive, insolent and arrogant, rude individual, a brash, foul-mouthed upstart, a conceited, self-important guttersnipe and an insult to the international community, as fit for the job as a pedophile janitor in a grade school.
Pentagon officials said that Russia has developed a very powerful weapon, which Western specialists have already dubbed as the "doomsday weapon"