The teams went to the changing rooms with the fixture suspended.
The scenes erupted after Wolves's second goal, scored by Matheus Cunha in the 78th minute, with clashes escalating and fans invading the pitch in an attempt to escape the confusion.
So far it's not clear what happened or whether any players or fans were assaulted, but some people in the crowd were seen bloodied and others were hauled away in handcuffs.
There are suggestions the issues may have developed due to some away fans having seats in the home end.
Some players from the home side were seen escorting their families away from the area.
The teams went to the changing rooms, with Wolverhampton leaving 0-2, the first goal coming through Portuguese forward Pedro Neto.
Play later resumed some 30 minutes after police and stewards calmed down the situation, picking up the match from 77 minutes - when Wolves' second goal was scored.
The clash between second-tier West Brom and Wolverhampton is a derby known as the Black Country Derby, which dates back to 1893, before the creation of the Football Association (FA) itself.
The region known as the Black Country is located in the Midlands of England, an urban area in the centre of the country and one of the birthplaces of the Industrial Revolution, with many coal, metallurgy and glass industries, among others.
