WILLIAM BRANGHAM: In the day's other headlines: Russian officials raised the death toll to 139 in the Friday night terror attack outside Moscow.

Today, the Kremlin talked of vengeance, as investigators worked the scene.

Stephanie Sy reports.

STEPHANIE SY: Crocus City Hall is a charged shell of debris and devastation.

Rescue workers search for bodies buried in its ruins days after attackers armed with rifles and knives laid waste to a rock concert.

It was the deadliest terror attack in Russia in decades.

Today, Russian President Vladimir Putin said radical Islamists were behind the massacre, but he also continued to implicate Ukraine, without evidence.

VLADIMIR PUTIN, Russian President (through translator): We know that the crime was committed by the hands of radical Islamists, whose ideology the Islamic world itself has been fighting for centuries.

We are interested in who ordered it.

STEPHANIE SY: Ukraine's President Volodymyr Zelenskyy denounced the suggestion.

Four main suspects appeared in a Russian court and appeared to have been beaten.

They're all of Tajik descent.

The Islamic State's Afghan branch, ISIS-K, posted this video claiming responsibility for the attack, a claim verified by the U.S., which had shared intelligence with Moscow ahead of time.

They have been comparing this for some time.

PAUL KOLBE, Senior Fellow, Harvard University: U.S. had given warnings a few weeks ago that this attack could take place.

STEPHANIE SY: Paul Kolbe is a former operations officer for the CIA with a focus on Eastern Europe and counterterrorism.

ISIS has attacked Russia a number of times over the years and has recently begun recruiting heavily from Central Asia, including Tajikistan.

PAUL KOLBE: Tajik workers are in Moscow, so they provide a -- both a willing and attractive recruitment pool for ISIS-K, because they have access to Russia, because they can be radicalized, and because they can be bought relatively cheaply.

STEPHANIE SY: The deadly attack has shaken Russia days after President Putin, fresh from securing a fifth term, promised stability.

For the "PBS NewsHour," I'm Stephanie Sy.

WILLIAM BRANGHAM: The attack in Moscow has done nothing to slow Russia's renewed bombardment of Ukraine's capital.

Today, missiles were fired at Kyiv for the third time in five days.

After some of the weapons were intercepted, debris fell on homes, injuring nine people.

Japan's Prime Minister Fumio Kishida has offered to meet with North Korea's Kim Jong-un.

It would be these two nations' first summit in nearly two decades if it happens.

Kim's sister Kim Yo-jong announced it today, but she insisted Tokyo accept the North's weapons program and ignore abductions of Japanese citizens.

Japan acknowledged it wants a summit, but with no preconditions.

The U.S. and Britain say China was behind a sweeping hacking campaign against lawmakers, defense contractors, and others.

Today, they sanctioned a company said to be a front for Beijing.

The U.S. Justice Department said it underscores -- quote -- "the potential for cyber-enabled foreign malign influence as we approach the 2024 election."

The European Union launched new antitrust probes into Apple, Google, and Meta today.

Regulators say the tech giants may be violating a new Digital Markets Act which aims to help consumers move freely between competing services and not be cornered by so-called gatekeeper companies.

MARGRETHE VESTAGER, Antitrust Commissioner, European Union: Consumers must have access to all the necessary information about their choices.

Gatekeepers can no longer prevent businesses from informing their users within the app about cheaper options outside of the gatekeeper's ecosystem.

WILLIAM BRANGHAM: The tech companies dispute the allegations, but they could be fined 10 percent of their global annual income.

Florida's Republican Governor Ron DeSantis has signed one of the country's most restrictive social media laws for minors.

It bars children under 14 from creating and owning accounts and requires parental permission for 15- and 16-year-olds.

If it withstands legal challenges, the law takes effect next January 1.

An early spring snowstorm churned across the Northern Plains and Upper Midwest today, while the South watched for thunderstorms and tornadoes.

It followed a weekend storm in New England that dumped more than two feet of snow and knocked out power to hundreds of thousands.

Police also reported hundreds of accidents.

Boeing is shaking up its executive suite amid a plague of safety problems.

The company announced today that Dave Calhoun will step down as CEO at the end of the year.

The board chairman and the head of its commercial airplanes unit are also leaving.

Boeing is under intense scrutiny after a 737 MAX lost a door panel mid-flight back in January.

Los Angeles Dodger Shohei Ohtani says he never bet on sports.

Ohtani spoke at a news conference today, five days after his interpreter was fired amid allegations that he engaged in illegal gambling and theft from Ohtani.

Ohtani said his interpreter had been -- quote -- "stealing money and has told lies."

Major League Baseball has opened a formal investigation.

And on Wall Street, stocks cooled a bit after last week's run-up to record highs.

The Dow Jones industrial average lost 162 points to close at 39313.

The Nasdaq fell 44 points and the S&P 500 was down 16.

Still to come on the "NewsHour": the fate of the most commonly used abortion pill goes before the U.S. Supreme Court; Tamara Keith and Susan Page break down the latest political headlines; and retired Supreme Court Justice Stephen Breyer discusses his new book on interpreting the constitution.