says shoppers flocked to buy on Prime Day, the annual summer discount extravaganza the e-commerce giant first concocted three years ago.

Share story says shoppers flocked to Prime Day — its self-proclaimed retail holiday for Prime subscription members — at an unprecedented rate, driven in large part by widespread demand for devices manufactured by the e-commerce giant.

The third incarnation of the annual summer discount extravaganza was extra-long — 30 hours instead of 24, starting Monday at 6 p.m. Pacific time. Just a few hours into the sale, Amazon was claiming “millions” of shoppers were purchasing at “record levels.”

By 3 p.m. Pacific time Tuesday, with nine hours still to go, Amazon said the blowout sale was “on pace to be the biggest global shopping event in Amazon history,” with customers in the U.S. ordering more than 6,000 deals per minute.

Amazon said the Echo, a voice-activated speaker and digital assistant, was the best-selling item in the U.S. By noon, Amazon had sold more than twice the number of Echo devices, in various versions, that it sold in the U.S. during last year’s entire Prime Day. (Around the globe, it was more than three times the number.)

Other hot sellers included Fire tablets and a genetics test dubbed 23andMe.

The first Prime Day was held in 2015, a Cyber Monday-like shopping event meant to encourage enrollment in Amazon’s $99 a year Prime loyalty program, which includes free shipping and other perks. Analysts say it may have brought in as much as $400 million in extra revenue.

Last year’s incarnation was termed by Amazon its “biggest day ever,” with sales surpassing the previous year by more than 50 percent in the U.S. and 60 percent around the globe.

This year it could be even bigger, analysts with Cowen say. For starters, it was available in three new markets — with Mexico, China and India joining 10 other countries.

Prime Day may also help drive more people to sign up for a Prime membership. Prime members are more frequent shoppers on Amazon, constituting a long-term boost to the company’s top line.

Cowen estimated there were 53 million Prime member households in the U.S. at the end of the second quarter, or 48 percent of total households. That’s up from 41 percent in the same quarter last year.

Competing retailers have jumped onto the Prime Day bandwagon. This year, Fry’s Electronics held a “Fry’s Day” offering free same-day delivery on 1,000 items. Best Buy had a “Big Deals Day.” Wal-Mart, Amazon’s biggest rival, didn’t follow along, however, choosing instead to showcase two-day shipping and discounts for store pickups, according to The Associated Press.

The retail holiday also proved to be a fulcrum for all sorts of social-media commentary on Amazon’s businesses.

On Twitter, activists who have been decrying the appearance of Amazon online ads on used the occasion to draw attention to their cause. “I celebrated #PrimeDay by cancelling my Prime membership,” one person tweeted.

The United Food and Commercial Workers International Union (UFCW), which represents retail workers, also put out a statement Tuesday, calling for Americans to “examine the high cost of Amazon’s business model.” In the statement, UFCW President Marc Perrone called Amazon’s vision, and reliance on automation, “brutal.”