hello welcome to the site
this sure sounds like the car might have gotten put into reverse by accident.
does this clunking noise sounds like its coming from the rear of the engine or under the car ?
well most cars now days have safety per cautions for this but with out seen this first hand its tough to pin point.
i can only go by your information you have provided.
but something got damaged could be a drive shaft. but once this is up in the air it should be evident
i wish i had some more positive info.
please take a moment to leave me some feed back as this is just as valuable as the accept.