Deadly Wisconsin school shooting. And, a pig kidney transplant ...

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Today's top stories

A grieving community gathered at a Madison, Wis., church last night after a 15-year-old girl opened fire at Abundant Life Christian School. A teacher and a student were killed in the shooting. The suspect, identified as Natalie Rupnow, who also goes by Samantha, died of what's believed to be a self-inflicted gunshot wound. Six other people were injured. Here's what else we know about the shooting.

???? Police confirmed that a second grader called 911 to report the school shooting, Sarah Lehr of NPR network station Wisconsin Public Radio says. They believe the shooting happened inside a study hall. As of late yesterday, police say two students remain in critical condition. Mireille Jean-Charles, a mother of three boys who go to the school, told Lehr that though they are uninjured, she expects they'll have emotional trauma for a long time. Authorities say they are still trying to piece together a motive behind the shooting. They recovered a handgun at the scene and are working to trace its origins.

President-elect Donald Trump held his first press conference since the election at his Mar-a-Lago resort in Florida yesterday. For over an hour, he discussed a range of topics, from concerns about his choice for health secretary, Robert F. Kennedy Jr., to his promise to bring prices down. NPR's Mara Liasson says Trump expressed that everything was pretty much perfect when he was in office before, and things will be great again with him returning to the White House.

???? Trump says everyone is trying to be his friend, and Liasson tells Up First there are some factors behind this. He is seen as a more legitimate president for his second term after winning the popular vote. There's also expected anticipation from the business community for a Republican president in office. People are approaching Trump differently and choosing their battles, believing his mind can be changed on certain ideas and policies.

For the first time, surgeons have implanted a new kind of engineered pig kidney into a living person. The milestone surgery is part of the quest to use genetically modified farm animals to save patients with failing organs. Towana Looney, a 53-year-old grandmother, received the surgery at the NYU Langone Health Hospital in New York City.

???? NPR's Rob Stein got exclusive access to the operating room during the seven-hour procedure, which took place on Nov. 25. The hope is that eventually, genetically modified pigs could provide an unlimited supply of kidneys, livers, hearts and other organs to help solve the organ shortage. Stein, who visited Looney two weeks after the surgery, says she is doing fine so far. Looney said she feels like she got a second chance at life. There are worries about pig organs spreading dangerous viruses to people, breeding and slaughtering pigs for their organs and experimenting on desperately ill patients. Deep dive

The Food and Drug Administration is considering banning Red No. 3, a petroleum-based food dye that has been used for more than 50 years in thousands of products, from candy to soda. The petition to ban the colorant has been under review since 2022, but an FDA spokesperson tells NPR a decision could come "soon."

???? The dye could cause cancer in animals in high doses, but the agency determined it was safe in the amounts used in food.???? California passed a law banning Red No. 3 last year. Lawmakers in 10 other states have introduced legislation to ban the dye in foods.???? California's Environmental Protection Agency reviewed research on synthetic dyes and found evidence that when consumed in food, they can negatively impact children's behavior.???? Red No. 3 has been banned or severely restricted in many countries, including Australia, Japan and countries in the European Union. Picture show

NASA technologist Rob Mueller dreamed up a new desert festival called RoboPalooza. It has some elements of other desert festivals, but there is a key difference. In addition to the live rock bands, food trucks and portable toilets, there are scientists using the Mojave Desert to test robots. The festival is sponsored in part by the Institute of Electrical and Electronics Engineers and focused on building a future for humanity in space. Essentially, the headliners are space robots and the people who spend their lives building them. See photos inside the festival.

3 things to know before you go Sotheby's is scheduled to auction one of the earliest tablets inscribed with the Ten Commandments tomorrow.This year is coming to a close, and NPR wants to know what key lessons you have learned. Share your story with us, and it could be featured in this newsletter on Dec. 29.An 18-month Senate investigation found that despite Amazon's claims of safe working conditions, it manipulated injury data to make warehouses appear safer.

This newsletter was edited by Suzanne Nuyen.