Is this normal?

I don't really know how to explain this, but I will try. So basically I will have this like really short panic attack randomly and will jump, my heart starts racing and I get really scared, sometimes I will like imagine some quick short scary scene like being hit by a train or something. I don't intentionally do this, sometimes I will even sometimes hear a sound accompanying the little vision thing. This will usually happen when I am trying to go to sleep, but sometimes it will happen while doing something in the day. This really scares me because I just started driving and don't wanna have this happen while driving my car. So is this maybe some sort of "condition" or just stress or what? Sorry if this is sorta confusing.