Play was temporarily suspended during an FA Cup tie between West Brom and Wolves after violent clashes broke out between fans causing some to spill onto the pitch.
Trouble flared during the Black Country derby at West Brom’s ground The Hawthorns after Matheus Cunha fired Wolves 2-0 up on 78 minutes.
Flares were thrown in the away fans’ stands while objects were thrown at Wolves’ Tommy Doyle as he prepared to take a corner. There also appeared to be pushing and shoving in the stand.
One man was seen being escorted off the pitch by police with his head covered in blood as fans chanted “let him die”. Another man was taken away on a stretcher.
Police said two people were arrested over the disorder and a third was arrested prior to the game for possession of an offensive weapon.
The Football Association (FA) has said it would investigate the “completely unacceptable” incident.
At one point, West Brom’s Kyle Bartley went into the crowd to take out his children amid the ugly scenes, which occurred in the corner of the West Stand and Birmingham Road End.
It was part of the ground which theoretically should have been holding solely home supporters but there was a lot of pushing and shoving, with some fans spilling onto the pitch.
Police and security rushed to a corner of the ground as the disturbance developed, but it was a long time before order could be restored. The referee stopped play shortly and the players were ushered off the pitch back to the dressing rooms.
There had earlier been pockets of trouble in other parts of the ground.
Play eventually resumed about 30 minutes later, but the incidents completely overshadowed what had been a hard-fought and absorbing fourth-round tie.
It was the first meeting between the clubs in front of supporters since 2012 and had been designated high risk, with security increased and the kick-off scheduled for 11.45am.
An FA statement said: “The disorder that occurred at the Black Country derby between West Bromwich Albion and Wolverhampton Wanderers is completely unacceptable.
“Safety and security are of the utmost importance, and the behaviour of those involved is dangerous and inexcusable.
“We will be investigating these serious incidents alongside the clubs and the relevant authorities, and the appropriate action will be taken.”
West Midlands Police said the two people were arrested for public order offences.
A spokesperson for the force said: “We had extra officers at this local derby and they responded immediately as disorder in the stands caused fans to spill onto the pitch.
“We worked with officials to get the game restarted as soon as possible. Another man was arrested before the game for possession of an offensive weapon.
“A man has been taken to hospital with head injuries.”