WASHINGTON — President Barack Obama phoned Russian President Dmitry Medvedev to discuss the rush-hour bombings on the Moscow metro.

A White House official said the two leaders spoke today and Obama conveyed the condolences of the United States.

The White House is calling the attack an "outrageous terrorist act."

Obama told the Russian leader the United States is ready to cooperate with Russia to bring to justice the attackers.

Earlier today, Obama condemned the bombings in a statement and called the attack "heinous."

The head of Russia's main security agency said a preliminary investigation places the blame on rebels from the restive Caucasus region, which includes Chechnya, where separatists have fought Russian forces since the mid-1990s.

By The Associated Press