Democrats who voted against the bill included Heidi Heitkamp (N.D.), Max Baucus (Mont.), Mark Begich (Alaska) and Mark Pryor (Ark.). Technically, Harry Reid voted "no," but that's a procedural move so that he has the right to bring the bill up again.
My colleague Sean Sullivan has a nice explainer on why the bill needed 60 votes to pass rather than a simple majority. But as political scientist Jonathan Bernstein explains here, this was essentially a GOP-led filibuster: "The correct thing to say about this is that the amendment was defeated by filibuster."
Meanwhile, an alternative Republican gun bill by Chuck Grassley and Ted Cruz that would have provided funding for gun-crime prosecutions, school safety, and mental health — but placed no new restrictions on gun ownership — was killed by a Democratic-led filibuster. That amendment received 52 votes, not enough to move forward.
A number of other amendments also failed to earn the 60 votes necessary to pass: Those included an amendment to stiffen penalties for “straw purchasers,” 58 to 42; a GOP-backed amendment to permit “national reciprocity” of concealed carry permits, 57 to 43; and a GOP plan to extend gun rights for veterans, including those deemed unable to manage their financial affairs, 56-44.
A full list of the gun-related amendments being voted on in the Senate can be found here.