(Reuters) – Wolverhampton Wanderers ran out 2-0 winners in their FA Cup fourth-round match at West Bromwich Albion on Sunday, but only after the match was interrupted due to clashes involving the two sides' supporters.
Wolves were leading 2-0 when projectiles were hurled on to one end of the pitch in the 82nd minute, sparking a brawl in a corner at The Hawthorns.
The FA called the disturbance that led to two arrests "completely unacceptable."
"Safety and security are of the upmost importance, and the behaviour of those involved was dangerous and inexcusable," the FA said in a statement.
"We will be investigating these serious incidents alongside the clubs and the relevant authorities, and the appropriate action will be taken."
West Brom said they would work with police and the FA to investigate.
"Any individual involved in the disorder will be subject to a club ban, in addition to potential criminal investigation," the club said.
Fans spilled on to the pitch, prompting players to leave the field. After a suspension of 38 minutes, the players returned and the match resumed, with the clock reset to 77 minutes 10 seconds, the time that Matheus Cunha had scored Wolves' second goal.
Pedro Neto had scored in the first half for Wolves who booked their berth in the fifth round with the victory.
"Of course we are disappointed with any type of incident like that," West Brom manager Carlos Corberan told ITV. "Unfortunately, the game was interrupted by this incident and now, we are unable to talk about the atmosphere our fans created, we can't talk about this aspect. We are totally disappointed by this.
"Everything before the incident was unbelievable, between both clubs it was very special and incidents like that we need to avoid."
Wolves manager Gary O'Neil called the disturbance "really disappointing."
"Up until that point it was a good tie with good atmosphere," O'Neil told ITV. "How people behave at football is really important and we need to look at that, make sure everyone is safe. When we came back out the atmosphere had gone, it was really sad to see."
"I know that the West Brom players' families were in that area which is a concern," he added. "I really hope everyone's OK, I'm not really sure what stoked it. We got the fixture played without any more trouble happening."
The delay prompted officials to push back the draw for the FA Cup fifth round -- originally scheduled for just before Liverpool's 1430 GMT kick-off against visiting Norwich City on Sunday -- to halftime of that game.