STOCKHOLM, Sweden — H&M on Thursday opened its doors to legions of shoppers trying to snag pieces of a new collaboration with designer label Balmain. Chaos ensued.In London, scuffles broke out on Regent Street as shoppers crammed their way through the store’s entrance. In Sydney more than a thousand shoppers lined up in the rain. In fact, queues wrapped around the block at stores all over the world, from San Francisco to Kuala Lumpur.Online shoppers didn’t have it much easier. H&M’s website couldn’t handle the load prior to the morning launch, and some would-be buyers — many of whom had waited hours in anticipation — found themselves staring at an error message, frantically refreshing a “Try Again” button. Most styles were sold out within minutes.With more than 100 pieces, the collection ranges from $18 rings to $650 dresses.Resellers hoping to make a quick buck began putting clothes on EBay immediately, with some auctions starting at $1,000 or higher. Meanwhile, angry shoppers flocked to H&M’s Facebook page to voice their discontent, sharing stories of the hours they’d spent trying to nab an item, only to come up empty-handed.Balmain, an haute couture French fashion house, became a buzzy brand with a younger set under the creative direction of Olivier Rousteing, a 29-year-old star designer who has a massive presence on Instagram. Its collaboration with H&M, announced in May, built up months of hype through ad campaign images and lookbooks.The crowds were unprecedented for H&M, the company said. The retailer has done many similar limited-time offerings in recent years, with such designers as Isabel Marant and Alexander Wang.“The interest for this launch has exceeded all previous collaborations, both in-store and online,” said Hacan Andersson, a spokesman for H&M. “Many customers started to line up early in all markets to be able to shop from the collection. In those markets that have launched the collections, the major part of the items are sold out, but there can still be returns in the following days.”By Kim Bhasin; editor: Alex Dickinson.