Greater Manchester Police says a bomb disposal unit has carried out a controlled explosion at Old Trafford stadium.
The controlled blast came soon after British military bomb disposal experts arrived at Manchester United's stadium to investigate reports of a suspicious package.
The Premier League match between United and Bournemouth was called off after the stadium, which has a capacity for more than 75,000 fans, was evacuated.
Two stands — The Sir Alex Ferguson Stand and the Stretford End — were evacuated about 30 minutes before the scheduled kickoff time of 3 p.m. local time (1400 GMT). Fans in other stands initially had been allowed to stay inside the stadium.
"Those inside OT are asked to remain seated while the forecourt is cleared of fans already evacuated from the stadium," United said.
Police with sniffer dogs were seen inside Old Trafford after the announcement was made.
Greater Manchester Police said on its Twitter page that people should "avoid the area if possible."
The rest of the Premier League games being played on Sunday, the final day of the league season, went ahead as scheduled.
United was vying with Manchester City to finish in fourth place in the Premier League and qualify for the Champions League. United needed to beat Bournemouth and for City to lose at Swansea.