Multiple bright white lights in front of black thunder clouds

Saw some very strange bright white lights in front of black thunderstorm clouds this afternoon. Saw one light at first and thought it was a plane (thinking to myself i would not want to be up there right now)… then five or six more of the bright white lights appeared out of nowhere. I said out loud “what in the hell is that?!?!), watched them for about 15 seconds, then grabbed my phone and called my husband to come upstairs. By the time I got back to the window (seconds later), they were gone. Very strange…