A mystery woman captivated Los Angeles police with her commanding operatic singing voice — and when they posted a video on Twitter, it immediately went viral.

The video shows the woman singing as she stands with bags on the platform of an underground Metro stop in Los Angeles. Her identity remains unknown.

The Los Angeles Times identified the aria as one of Puccini’s. The newspaper said the video was taken by a police officer, who happened to be standing on the platform when the woman began singing.

Some residents in the area said they’ve seen the woman around for the past 10 years, according to ABC Los Angeles station KABC.

Others have spotted her playing the violin outside shopping malls and have heard her speaking in Russian.