The number of murdered in the attack on Monday in the St. Petersburg, Russia metro is up to 14.
Some 50 people were wounded in the suicide attack, which was perpetrated by a terrorist from Kyrgyzstan.
Following the attack, US President Donald Trump offered condolences to Russian President Vladimir Putin.
“President Trump offered the full support of the United States government in responding to the attack and bringing those responsible to justice,” the White House said in a statement.
Prime Minister Netanyahu sent a message of condolence to Russia, saying "the citizens of Israel stand alongside the Russian people at this difficult time."
No group has yet claimed responsibility for the attack. The administration of St. Petersburg has declared three days of mourning starting from Tuesday.
Russian Prime Minister Dmitry Medvedev said victims would be provided with "all necessary assistance." He said in a message: "My most sincere condolences to the families and friends of the victims of the explosion. The pain is shared by us all.”