Much of the Internet worldwide was hit early Tuesday by an outage traced to the network and security provider Cloudflare, reports The Hill.

It lasted just 23 minutes, but likely impacted “millions” of websites, mostly in Europe, the United States and parts of Australia. The exact cause remains unclear.

“According to Cloudflare, it hosts over 16 million internet properties, and the company powers internet requests for around 10 percent of the Fortune 1,000 companies and for more than one billion IP addresses every day,” The Hill says.

It was the second major Internet outage in two weeks, reports BGR, an online consumer-electronics news site. The first, last week, was traced to Verizon.

After getting things running again, Cloudflare released this statement:

“Major outage impacted all Cloudflare services globally. We saw a massive spike in CPU that caused primary and secondary systems to fall over. We shut down the process that was causing the CPU spike. Service restored to normal within ~30 minutes. We’re now investigating the root cause of what happened.”

CEO Matthew Prince adds, “This wasn’t an attack. This was a bug in our systems.”