Amazon customers are shopping at "record levels" worldwide this Prime Day, Amazon said Tuesday morning.
The 30-hour event began Monday night at 9 p.m. ET. By 4 a.m. Tuesday, Amazon said that millions of Prime members globally had already shopped the website for bargains and "lightning deals."
Amazon didn't offer details on what it called record levels of shopping — whether it represented the number of shoppers or the amount sold.
In the U.S., the Amazon Echo was the best-selling item by 4 a.m., Amazon said. The Echo was selling for $89.99 on Prime Day, half the usual price. Other best-selling deals include those for Amazon's Echo Dot, a 23andMe DNA test and Amazon's Fire 7 Tablet with Alexa.
To take advantage of the discounts, shoppers must be Amazon Prime members, which costs $99 a year and includes perks like free, two-day shipping, access to Prime Video and Prime Music.
Amazon's stock closed Monday up 1.8 percent. Shares were falling 0.8 percent Tuesday afternoon, not moving much one way or the other.
The shopping event, in its third year, is known for offering shoppers some of the best deals on Amazon's own products — particularly electronics. In 2016, Prime Day was the "biggest day ever" for Amazon devices globally and for each Amazon device category, including the Fire TV, Fire tablets, Kindle e-readers and Alexa-enabled devices, Amazon said.
This year, new deals are hitting Amazon's website as often as every five minutes and will be available to Prime members until 3 a.m. ET Wednesday.
As of Tuesday morning, some products on Amazon.com had already sold out, putting customers on waiting lists as they scoured the best deals on everything from toothbrushes to laptops, Under Armour gear to trail mix.
Many of Amazon's competitors, meanwhile, were seen hoping to capitalize on the heavier-than-normal online shopping traffic Tuesday, rolling out their own deals. Some even chose to take a swing at Amazon. EBay, for example, had a banner on its website reading, "Their Prime Deal Is Our Everyday Deal."