Happening Today: Russia Probe, Manchester Bombing, Epilepsy, Ariana Grande

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Raids, Arrests as On-Edge UK Seeks “Network” of Attackers

Security forces rounded up more suspects in the deadly Manchester concert blast and soldiers fanned out across the country to national landmarks as an on-edge Britain tried to thwart the possibility of additional attacks. Officials scoured the background of the British-born ethnic Libyan identified as the bomber, saying he was likely part of a wider terrorist network. Additional arrests were made both in Britain and in Libya in the bombing that killed 22 people and wounded scores more. Among those taken into custody in Libya were the suspected bomber's father and his younger brother, the latter of whom confessed to knowing "all the details" of the attack plot, Libyan anti-terror authorities said. Abedi was known to U.S. authorities before the attack, multiple U.S. intelligence and law enforcement officials told NBC News. Meanwhile, officials probed possible travel by the alleged bomber, looking for clues to new threats.

Russia Hoped to Sway Trump Via Advisers, Report Says

A new report says U.S. intelligence services obtained information during the 2016 presidential election that showed senior Russian officials discussing how to influence Donald Trump through his campaign advisers. That's according to The New York Times, which cites three current and former American officials. The report says the Russians zeroed in on Trump campaign chairman Paul Manafort and Michael Flynn, a former head of U.S. military intelligence who was a key Trump campaign adviser. The report says the Russian officials thought Manafort and Flynn could be used to influence Trump's views on Russia. The Times says some of the officials bragged about ties to Flynn. Others thought they could use Manafort's association with former Ukrainian President Viktor Yanukovych, who led a pro-Russian political party, to their advantage.

House Candidate Charged After Clash With Guardian Reporter

The Republican candidate for Montana's sole congressional seat was charged with misdemeanor assault after witnesses told police Greg Gianforte grabbed a reporter by the neck and slammed him to the ground the night before polls close in the nationally-watched election. Gallatin County Sheriff Brian Gootkin made the announcement in a statement posted to the county website. Gianforte would face a maximum $500 fine or 6 months in jail if convicted. The statement added that the reporter's injuries did not meet the legal definition of felony assault. Gianforte was in a private office preparing for an interview with Fox News when reporter Ben Jacobs of The Guardian came in without permission, campaign spokesman Shane Scanlon said. In an audio recording posted by the Guardian, the reporter asks the congressional candidate about the GOP's health care bill, which was just evaluated hours earlier by the Congressional Budget Office. He has until June 7 to appear in court on the charge.

Marijuana Extract Helps Some Kids With Epilepsy, Study Shows

A medicine made from marijuana, without the stuff that gives a high, cut seizures in kids with a severe form of epilepsy in a study that strengthens the case for more research into pot's possible health benefits. "This is the first solid, rigorously obtained scientific data" that a marijuana compound is safe and effective for this problem, said one study leader. He said research into promising medical uses has been hampered by requiring scientists to get special licenses, plus legal constraints and false notions of how risky marijuana is. The study was published by the New England Journal of Medicine. For years, desperate patients and parents have argued for more research and wider access to marijuana, with only anecdotal stories and small, flawed studies on their side. The new study is the first large, rigorous test — one group got the drug, another got a dummy version, and neither patients, parents nor doctors knew who took what until the study ended.

Ariana Grande Suspends Tour Following Manchester Attack

Ariana Grande is suspending her world tour through June 5 following the Manchester Arena attack at her concert that left 22 dead. "Due to the tragic events in Manchester the Dangerous Woman tour with Ariana Grande has been suspended until we can further assess the situation and pay our proper respects to those lost," a statement from the singer's management company reads." The 23-year-old pop star is on a European leg of her "Dangerous Woman Tour" and canceled shows scheduled for Thursday and Friday at the 02 Arena in London. The suspended tour means she also will miss a May 28 stop in Antwerp, Belgium, two concerts in Lodz, Poland, and shows in Frankfurt, Germany, and Zurich, Switzerland. Grande has kept a low profile since Monday's Manchester Arena blast. She took to Twitter afterward to say she was "broken" and "i don't have words."

Serena Williams Accepts New Challenge

Tennis star Serena Williams has 39 Grand Slam titles, four Olympic medals, major endorsement deals and her own line of clothing and accessories. Now she is embarking on a new mission: She says she wants to help tech companies diversify their workforces and solve one of the industry's most vexing problems. Williams, 35, will get her chance as she joins a Silicon Valley boardroom. Online poll-taking service SurveyMonkey announced Williams' appointment to its board, along with Intuit CEO Brad Smith. Williams didn't offer specifics about her goals as a corporate director. She implied that her very presence can help push the company — and, by extension, the industry as a whole — in a more diverse direction. Individual board members don't usually exert great influence over the companies they oversee, although they are often compensated handsomely in cash and stock for their part-time work. SurveyMonkey, a private company, didn't say how much Williams will be compensated.