A capacity crowd at Old Trafford impeccably respected the minute's silence in memory of the Munich air disaster.
United and City fans raised their commemorative scarves around the ground and stood in tribute to the 23 people, including eight of the famed 'Busby Babes', who died in the air crash 50 years ago last Wednesday.
But during the minute's silence, what appeared to be loud bangs were heard coming from outside the stadium.
Fears were heightened after a minute's silence at Wembley on Wednesday ahead of England's meeting with Switzerland was cut short after some spectators disrupted the tribute.
Legendary City goalkeeper Frank Swift was among eight journalists who also perished when the plane carrying United home from a European Cup match in Belgrade crashed on take-off after refuelling in Munich.
Survivors of the tragedy were among the crowd for the Old Trafford derby, which was the culmination of a week of events marking the 50th anniversary.
Both clubs wore special kits for the match and United boss Sir Alex Ferguson and City counterpart Sven-Goran Eriksson placed wreaths in the centre spot ahead of the period of silence.