MOSCOW — The death toll from last week's Moscow concert hall attack rose to 143, Russian authorities said Wednesday. Around 80 other people wounded in the siege by gunmen remain hospitalized.

The Friday night massacre in Crocus City Hall, a sprawling shopping and entertainment venue on the northwestern outskirts of Moscow, was the deadliest extremist attack on Russian soil in nearly two decades. At least four gunmen toting automatic rifles shot at thousands of concertgoers and set the venue on fire.

An affiliate of the Islamic State group claimed responsibility for the violence, while U.S. intelligence said it had information confirming the group was responsible. French President Emmanuel Macron said France also has intelligence pointing to “an IS entity” as responsible for the attack.

The updated fatalities from Russia’s Emergencies Ministry didn't state the number of wounded, but Health Minister Mikhail Murashko said earlier Wednesday that 80 people were in hospitals and another 205 had sought medical treatment from the attack.

Russia's Federal Security Service, or the FSB, said it had arrested 11 people the day after the attack, including four suspected gunmen. The four men, identified as Tajik nationals, appeared in a Moscow court on Sunday on terrorism charges and showed signs of severe beatings. One appeared to be barely conscious during the hearing.

Russian officials, however, have insisted that Ukraine and the West had a role , claims that Kyiv vehemently denies. Ukrainian President Volodymyr Zelenskyy accused Russian counterpart Vladimir Putin of trying to drum up fervor as his forces fight in Ukraine.

FSB chief Alexander Bortnikov has also alleged, without providing evidence, that Western spy agencies could have been involved. He repeated Putin’s claim that the four gunmen were trying to escape to Ukraine when they were arrested, casting it as proof of Kyiv's alleged involvement.

But that assertion was undercut by Belarus’ authoritarian president, Alexander Lukashenko, who said Tuesday that the suspects were headed for Ukraine because they feared tight controls on the Belarus border.

The Islamic State group, which lost much of its territory following Russia’s military action in Syria after 2015, has long targeted Russia. In October 2015, a bomb planted by IS downed a Russian jetliner over the Sinai desert, killing all 224 people aboard, most of them Russian vacationers returning from Egypt.

The group, which operates mainly in Syria and Iraq but also in Afghanistan and Africa, also has claimed several attacks in Russia’s volatile Caucasus and other regions in the past years. It has recruited fighters from Russia and other parts of the former Soviet Union.

The United States warned Moscow two weeks before the massacre about a possible imminent attack. Three days before the tragedy, Putin denounced the U.S. Embassy’s notice on March 7 urging Americans to avoid crowds in Moscow, including concerts, calling it an attempt to frighten Russians and “blackmail” the Kremlin before the Russian presidential election.

Bortnikov said Russia was thankful for the warning but described it as very general.