The chief of Greater Manchester Police has blamed retailers after officers were called to seven Tesco stores across Greater Manchester to deal with crowds at Black Friday events.
In a video posted to YouTube, Sir Peter Fahy said three people had been arrested - including one who threatened to "smash" a staff member's face in, while one woman had her wrist broken.
He added that the events had been "totally predictable", and that he was "disappointed that stores did not have sufficient security staff on duty".
[Retailers] should have planned much more effectively and had the appropriate level of security and stewards to make sure people could go around their stores safely.
Fahy's comments came as the UK's first major "Black Friday" descended into chaos. Crowds were seen pushing and shoving as retailers launched heavy discounts.
The New West End Company reported that footfall on Oxford Street in central London was up 19.5 per cent year-on-year, while sales on the street were expected to hit £150m by the end of the weekend. Retailers on the street marked the occasion with their "longest trading day ever", said the organisation.
Although "Cyber Monday" - the first Monday of December - is traditionally the time when shoppers flock to online retailers, this morning retailers' websites began to buckle under the pressure from the sheer volume of shoppers. While some websites went down entirely, others - such as Currys - introduced a virtual "queueing" system, which controlled the amount of traffic going to the site.
Online voucher site VoucherCodes said the situation is unlikely to improve on Monday, with nine million shoppers expected to take advantage of Cyber Monday deals.
“For many consumers the last weekend in December also marks the last weekend before the Christmas frenzy begins and retailers respond to this with huge discount offers and promotions," said Anita Nafik, the website's lifestyle editor.