LONDON - Fans pelted Manchester United's team bus with bottles and other missiles outside West Ham United's ground on Tuesday, injuring two and forcing a delay to their Premier League game.
Visiting captain Wayne Rooney said the vehicle was "smashed up".
Video footage circulating on social media showed the team bus being hit by a hail of cans and bottles as it arrived at West Ham's Boleyn Ground in east London.
Police on horses and wearing helmets separated the black coach from the crowd, some wearing West Ham shirts, as onlookers recorded the scene on mobile phones.
Kick-off in West Ham's final game at the landmark stadium was delayed by 45 minutes until 1930 GMT after the incidents.
One image showed a gaping hole in a pane of protective glass.
Rooney told Sky Sports television: "We know it's a big game for West Ham, a big night for them, leaving the stadium, but I'm sure West Ham as a club will be disappointed with what the fans have done." "It wasn't nice," he said.
A short video surfaced on Twitter that seemed to show Manchester United's players lying on the floor of the bus as it came under attack.
Midfielder Jesse Lingard appeared to have filmed the video on his smartphone and could be seen pulling faces at the camera.
Phil Jones, Michael Carrick and Adnan Januzaj, all wearing their club suits, could also be seen, squeezed together on the floor in the space between the two aisles of seats.
West Ham co-chairman David Sullivan blamed United for not arriving earlier however. He claimed the bus had not been damaged.
"I don't understand why United couldn't get here at four o'clock," he told BBC Radio 5 Live. "They could have got here early. They knew it would be busy. It's crazy.
"There was congestion in the street and they couldn't get the coach in. There were people around the coach, but there was no attack on the coach.
"If you check the coach there won't be any damage to it." But United manager Louis van Gaal echoed Rooney, saying: "What do I have to tell? The images tell everything." "The way we have been received is not the proper way, of course. That makes all the influence on the players and that is a pity," he added.
"We are aware that a number of items were thrown towards Man Utd's coach this evening," the Metropolitan Police football unit wrote on Twitter.
"Where criminal offences are committed we will seek to work with the clubs to bring those that break the law to court." The Boleyn Ground has been West Ham's home since 1904.
The club are moving to the nearby Olympic Stadium at the end of season and were due to stage a farewell ceremony following Tuesday's game.
Manchester United had also been delayed arriving for their game at Tottenham Hotspur, also in London, a month ago, when kick-off again had to be put back.
On that occasion, traffic congestion was blamed.