As-yet-unknown gunmen shot and gravely wounded the mayor of Ukraine's second-largest city, Kharkiv, in the back on Monday. The mayor, Hennady Kernes, is listed in "grave but stable" condition after a series of operations on his chest and abdomen. Kharkiv, a city of 1.5 million, is the only major population center in eastern Ukraine where the pro-Moscow insurgency has had little success.

The Kernes shooting kicked off a day of violence in eastern Ukraine. Pro-Russia militants seized a government building in yet another town, Kostyantynivka, and hundreds of men in military fatigues shouting "Russia!" attacked a 1,000-strong rally for Ukrainian unity in Donetsk using batons, bricks, iron bars, and stun grenades to beat and injure dozens of peaceful marchers. A similar clash occurred in Kharkiv on Sunday, with militants attacking a pro-unity march by fans of rival soccer teams.

Pro-Moscow militants are also still holding seven European observers from the Organization for Security and Cooperation in Europe and five Ukrainian security personnel who were accompanying them. In what passes for good news, one of the OSCE observers, a Swede, was released for health reasons. And Russia's defense chief told U.S. Defense Secretary Chuck Hagel on the phone that Russia won't invade Ukraine, according to the Pentagon. That's good, though if I were in Ukraine I'd want that in writing, signed by Russian President Vladimir Putin. Peter Weber

Nearly 21 percent of high school seniors say they vaped within the past 30 days, up from 11 percent one year ago, a new survey out Monday says.

The Monitoring the Future survey has been in existence for 44 years, asking teenagers whether they use drugs, drink alcohol, or smoke, and this was the most dramatic spike in its history. The survey is funded by the National Institute on Drug Abuse, and its director, Nora Volkow, said the report is "very worrisome. We are very concerned about the increase in vaping."

Vapors from e-cigarettes contain high levels of nicotine, and doctors fret about how this affects brains that are still developing. The survey also found that more teens now believe that they are simply breathing in flavors when they vape, not understanding that they are indeed inhaling nicotine. Catherine Garcia

The winner of the 2018 Miss Universe pageant is Miss Philippines Catriona Gray.

The 24-year-old was crowned the winner Sunday night in Bangkok. She defeated 93 other contestants, including first runner-up Miss South Africa Tamaryn Green and second runner-up Miss Venezuela Sthefany Gutierrez. This was the first year that the selection committee was comprised solely of women.

Born in Australia, Gray entered her first pageant at age five, and studied music at the Berklee College of Music in Boston. Catherine Garcia

Since Wednesday, thousands of demonstrators have filled the streets of Budapest at night, protesting against Viktor Orban, the country's right-wing prime minister, and new laws ushered in by his Fidesz party.

Sunday's protest was the largest, with at least 10,000 people gathering to walk from Heroes' Square to parliament. During the spring election, Fidesz received 49 percent of the popular vote, but the party changed the rules so its lawmakers control two-thirds of the parliament. On Wednesday, Fidesz lawmakers approved a measure that critics have dubbed the "slave law," which lets employers ask staffers to work up to 400 hours in overtime every year. Under the law, the overtime payments could be postponed for up to three years.

Even Orban's own supporters don't agree with the law, with a new Republikon Institute poll showing that 63 percent disapprove. The protests are being organized by unions, students, and opposition parties. In addition to the law being changed, these demonstrators are calling for a free press and an independent judiciary. The protesters have been peaceful, Reuters reports, but police officers still fired tear gas into the crowd on Sunday night. Catherine Garcia

Janet Fein celebrated her retirement at age 77 by going back to college.

In 2012, Fein retired from her job as a secretary at an orthopedic hospital in Dallas, and immediately enrolled in classes at the University of Texas at Dallas. "I didn't have anything to do in retirement and I didn't think that playing bingo was up to my speed," she told The Associated Press. Fein, now 84, loved writing papers and doing homework, and didn't let anything get in her way — she kept up with everything even as she moved into an assisted living facility and had to start using a walker and oxygen tank.

This week, Fein will receive her bachelor's degree in sociology. Through a state program, Texans 65 and older can take up to six credits per semester at a public university for free, and last year, about 2,000 people participated, the Texas Higher Education Coordinating Board said. Fein believes in the importance of learning — after raising her five kids, she took classes for 20 years and received her associate's degree in 1995 — and has inspired one of her caregivers, Renee Brown, to go back to school at 53 to become a licensed vocational nurse. "She said, 'Renee, you can do it. If I can do it you can do it and you will feel so good about it,'" Brown told AP. Catherine Garcia

Colin Kroll, the co-founder of Vine and HQ Trivia, was found dead Sunday inside his New York City apartment. He was 34.

Kroll was discovered by police officers after his girlfriend called and asked for a wellness check, CNN reports. The cause of death has not yet been determined.

HQ Trivia, a trivia game app, was launched in 2017. Kroll became CEO of HQ Trivia's parent company, Intermedia Labs, earlier this year after his business partner Rus Yusupov was forced out, Recode reports. Recently, Kroll was accused by an HQ Trivia employee of "inappropriate and unprofessional behavior;" the matter was investigated and "yielded no concerns," the company told Recode. Catherine Garcia

A new report prepared for the Senate Intelligence Committee, the first to study millions of posts from the 2016 presidential campaign provided by Facebook, Twitter, and Google, says that Russians working at the Internet Research Agency posted on every major social media platform photos, videos, and messages to help get President Trump elected, and continued the effort to support him once in office, The Washington Post reports.

The Post obtained a draft of the report, compiled by Oxford University's Computational Propaganda Project. Researchers found that at certain points, like during presidential debates, disinformation campaigns ramped up, with different groups receiving targeted messages: for example, conservatives saw posts about gun rights, while black voters saw false information about how to vote.

"What is clear is that all of the messaging clearly sought to benefit the Republican Party — and specifically Donald Trump," the report says. "Trump is mentioned most in campaigns targeting conservatives and right-wing voters, where the messaging encouraged those groups to support his campaign. The main groups that could challenge Trump were then provided messaging that sought to confuse, distract, and ultimately discourage members from voting."

The tech companies were all extremely slow to realize what was going on, the report says, even though the Russians slipped up several times, like paying for ads with rubles. Social media, the report states, went from a "natural infrastructure for sharing collective grievances and coordinating civic engagement to being a computational tool for social control, manipulated by canny political consultants and available to politicians in democracies and dictatorships alike." Read more about the report at The Washington Post. Catherine Garcia