A "Live Update" page on NPR keeps the same URL, but the content changes at the day progresses. This allows people to keep tabs on a story by refreshing the page, or by the page auto-refreshing. The original story was posted at 9:33 AM ET, with the headline "Diehard Trump Supporters Gather In The Nation's Capital To Protest Election Results".
Through the day the story was updated, with the last update at 3:08 PM ET, shortly after rioters were photographed on the Senate chamber floor. The headline for the final version of the story was "Trump Supporters Storm U.S. Capitol, Clash With Police"
However the story still had the original time under the headline, with the "Updated" time under the photo. This led to some people thinking the "Storm the Capitol" story was posted BEFORE the Capitol was stormed (when it was actually updated at 3:08, nearly 30 minutes after the first reports of windows being broken.
A useful quick check in cases like this is to look at the URL (the web address), as it often contains the original headline. In this case it is:
https://www.npr.org/sections/congress-electoral-college-tally-live-updates/2021/01/06/953616207/diehard-trump-supporters-gather-in-the-nations-capital-to-protest-election-resul
Example rumor: