The pro-Moscow president of Chechnya was killed along with a reported 40 or more others by an explosion during an annual parade to mark Moscow's defeat of Nazi Germany. The blast appeared to mark a setback for Russian President Vladimir Putin's claim that the long-running conflict in Chechnya is over.

Officials say the bomb was planted under the reviewing stand where Chechen President Akhmad Kadyrov and other top officials were watching the parade.

The blast tore a huge hole in the stand and spectators scattered in panic. Hours later, Russian President Putin confirmed that Mr. Kadyrov was among the dead.

Security officials say the bomb was hidden inside the concrete of the stadium, which is why it was not detected during a security sweep before the parade.

Mr. Putin later blamed the violence on terrorists and said they could expect swift retribution.

Mr. Kadyrov was elected president last October in a vote that was heavily criticized by international observers. Rebel groups have accused him of treason and had tried several times before to assassinate him.