Tim Brockmeier and Philipp Hofmeister, working for German broadcaster Hessischer Runfunk, said their headsets were ripped off and that they were physically assaulted by West Ham fans after Michail Antonio had equalized for the hosts in the first half.
The pair said the West Ham fans were sitting directly behind them and had been angered by them cheering loudly when Frankfurt took the lead in the first minute of the match.
The incident was captured on the live broadcast.
“We are being attacked from behind by the English fans, that’s why we were unfortunately gone for a short time,” Hofmeister said on the broadcast.
“So we are being attacked from behind. And our colleague Tim just had his headset thrown to the ground, so we really have to be a bit careful what we do here.”
West Ham told CNN it had identified two offenders and was continuing its investigation.
“In line with our zero-tolerance approach, the offenders’ details have also been passed onto the police, who will now conduct their own investigation,” a West Ham spokesperson said.
“If the offenders are found guilty, they will be given an indefinite ban and not be allowed to enter London Stadium, nor travel with the Club. Behavior of this kind is unacceptable and will not be tolerated at West Ham United.”
CNN has reached out to London’s Metropolitan Police but has not yet received a response.
The commentators later thanked members of the West Ham media department who moved them to a new seat at halftime.
“First of all, I’m sorry to all of you who might be used to a different performance from us,” Brockmeier added during the broadcast, after they were moved.
“We were hoping to deliver in the first half, but if you constantly have the feeling that something could come from behind, a punch or some other blow or maybe something worse, then you are not free and can not concentrate on the game.”
Gabriele Holzner, program director of the Hessischer Rundfunk, also condemned the attack on its reporters.
“A soccer stadium is not a lawless space,” Holzner said in a statement to CNN.
“We expect the organizing club to ensure a safe environment for all journalists – including those of the visiting team – so they can do their job without fear of assault.
“Punches and physical violence are not tolerable under any circumstances.”
West Ham eventually lost the first leg 2-1, with the return fixture set for May 5 in Germany.