Three of the four victims killed when gunfire erupted at a birthday party in Stockton, California were children, according to officials. It comes as police search for the suspect or suspects who took the fatal shots. Both the House and Senate have started inquiries into a second strike on an alleged drug boat in the Caribbean last September that killed the survivors of an initial strike. NBC News' Kelly O'Donnell reports. NBC News' Steve Patterson reports. Luigi Mangione, the suspect accused of murdering UnitedHealthcare CEO Brian Thompson nearly a year ago, will return to a New York courthouse on Monday for a critical hearing that could impact the evidence allowed in his trial. NBC News' Ellison Barber has more. Secretary of State Marco Rubio met with Ukrainian officials in Florida for a round of peace discussions. Officials from both countries called the meeting "productive." NBC News' Raf Sanchez reports. A major winter blast impacting millions across the country snarled the busiest travel day of the year on Sunday, with wintry conditions leading to car accidents on roads and long lines at airports. NBC News' Valerie Castro reports from Chicago's O'Hare International Airport. With the holiday shopping season in full swing, Cyber Monday is poised to break records after an already record-breaking Black Friday. NBC News' Brian Cheung has a preview. Denver Broncos linebacker Alex Singleton is set to return to the football field on Sunday night after undergoing surgery for testicular cancer. The co-captain, who leads the Broncos in tackles, even played in an NFL game after receiving the diagnosis, before being sidelined for weeks during his treatment. NBC News' Hallie Jackson has the story.