A controlled explosion has been carried out at Old Trafford after a suspect package was found before Manchester United's match against Bournemouth.
Greater Manchester Police described the device as "incredibly lifelike" but confirmed it "wasn't viable".
The Sir Alex Ferguson Stand and the Stretford End were evacuated before the game and sniffer dogs brought in.
Kick-off, due at 15:00 BST, was delayed and shortly afterwards the match was abandoned on police advice.
A bomb disposal team carried out the explosion at about 16:30 BST.
Just under two hours earlier, an "operation red code" alert had been heard over the public address system, and the players who were warming up had left the field.
Fans were then advised that, because of "the discovery of a suspect package in the north-west quadrant of the ground, the match has been abandoned for today on police advice".
Supporters who were still in the ground were advised to stay in their seats while the forecourt was cleared of fans who had been in the two stands that were evacuated.
While the evacuation was occurring, Manchester United executive vice-chairman Ed Woodward spoke to Premier League chairman Richard Scudamore about the game being called off, BBC Sport's football correspondent Phil McNulty revealed.
The Premier League has announced it is looking to rearrange the match as soon as possible.
"The game will definitely need to be played but there are logistical issues that need to be resolved," a statement read.
However, they cannot even start to begin discussing them until the police have done what they need to do here [at Old Trafford]."
Speaking before the controlled explosion was carried out, assistant chief constable John O'Hare of Greater Manchester Police said their priority "was to ensure the safety of everyone in the stadium and surrounding area".
He said "military colleagues" were assisting with the incident, adding: "We don't make these decisions lightly and we have done this today [abandoned the match] to ensure the safety of all those attending."
United players were seen leaving the ground shortly after 16:30 BST. BBC commentator Conor McNamara said he saw Bournemouth players and staff boarding their team bus outside Old Trafford around an hour later.
The south coast club later confirmed they would be flying back to Bournemouth on Sunday night.
'A dark day in Premier League history'
Manchester United had started Sunday with an outside chance of qualifying for next season's Champions League by finishing fourth in the Premier League.
However, Manchester City's draw against Swansea in their final game means United are effectively out of the running, with City three points clear of United and possessing a goal difference that is 18 better than that of their rivals.
Sean Bones, vice-chairman of the Manchester United Supporters' Trust, said: "It is obviously a dark day in Premier League history. We have obviously got to give our thanks to the club and the authorities for getting supporters out of the ground safely and home to their families.
"If it turns out there was a bomb at Old Trafford, it is obviously a concern that we have these type of people in our midst and it is going to have a huge effect on security at football matches in the future."
The first indications that all was not well at Old Trafford came when stewards swung into action and fans were evacuated from the Stretford End.
"Thousands of supporters were already inside Old Trafford when, in a well-organised drill, supporters in the giant Sir Alex Ferguson Stand were also moved out as a 'Code Red' operation was announced over Old Trafford's public address system.
"Those in the Sir Bobby Charlton Stand, where some had already gathered in the directors' box, and the East Stand, where the Bournemouth supporters were assembled, were told to stay calm and remain in their seats.
"Bournemouth's players had started their warm-up but they left the pitch swiftly once it became clear a security operation was under way as police moved in and a helicopter flew above the ground.
"Some Bournemouth fans were unhappy at the regular announcements to remain in their seats, especially after word had swept around Old Trafford that the game had been called off, but safety was understandably paramount.
"Once the official announcement was made to those still inside the stadium, there was an orderly exit, although roads around the ground remained cordoned off by police and stewards as fans were shepherded away from the area where police were carrying out an inspection of the suspect package."