David Forster was working behind the bar in the away fans' section of the stadium during Sunday's game against the Black Cats.
The 27-year-old today told how several Red Devils' fans turned violent, ripping tills from the bar area before trying to steal the money inside.
Mr Forster, of Murton, who is employed by a catering firm and is in his third season working at the stadium, said: "You could see before the match started that they were getting angrier and angrier.
"Just before the game kicked off they went ballistic. They were just vultures going after the money. It looked like it would turn violent for a couple of minutes.
"The staff weren't hurt, but some were feeling shaken. How could the police let it get to that stage?"
"They need to get them (the fans) on banning orders."
Sunderland 0 Man Utd 1
Superintendent Steve Neill of Northumbria Police said: "Additional officers were deployed in the key areas of the bar, particularly at half time, to prevent crime and disorder.
"These officers worked closely with club staff to ensure fans and staff were kept safe." A Northumbria Police spokesman said: "During the match police received a report that a member of staff had stolen a quantity of cash from the till at a kiosk.
"An 18-year-old man from West Boldon has accepted a caution for an offence of theft.
"A man was also arrested after an allegation that money had been taken from a till by a fan.
"A 24-year-old man from Ashton-under-Lyne was arrested on suspicion of theft and has been released on police bail.
Sunderland AFC safety manager Paul Weir said: "Activity on the concourses was monitored before and during the game, especially at half time, when police and steward resources were deployed on the concourse.
"This was done to ensure Manchester United fans could obtain refreshments in comfort and safety.
"Additional resources were deployed inside the kiosks to ensure the safety of the staff serving the Manchester United fans with those refreshments."