WASHINGTON — An impromptu performance of the Christmas classic “O Holy Night” recorded in the Union Station Metro station has gone viral.

Tymara Walker, 38, a professional singer in Las Vegas was visiting family in D.C. earlier this month, when she decided to try out the acoustics inside the Metro station on a Saturday afternoon, The Washington Post reported.

The minute-long clip spread on social media, racking up thousands of views on Facebook and Instagram.

Walker’s spine-tingling rendition is drawing raves, but the whole performance might never have happened except Metro happened to be single-tracking that weekend. Walker tweeted she was waiting on the platform for about 20 minutes because one track was down that day.