Microsoft’s Bing search engine was banned in China on Thursday, according to the Associated Press. Microsoft confirmed to Fortune that the search engine has been banned in China and said that it was determining its “next steps.” Bing users in China quickly took to social media, where they railed against the ban and questioned why they couldn’t use Bing any longer.

While no official word has come down on why Bing has been banned in China, Bloomberg is reporting, citing sources, that the ban is not due to censorship. Instead, the Bloomberg sources said that it was a mistaken technical error that took Bing down and not an attempt at censorship.

A slew of U.S. companies have been banned from China’s Internet. The Chinese government keeps an iron grip on Internet in the country and bans access to sites that promote free speech under the guise of national security. Google, Facebook, YouTube, and many other prominent sites are all banned in the country.

Microsoft’s Bing (MSFT) was able to stay up in China because the company complied with the Chinese government and removed certain foreign websites from its search results. Google’s search doesn’t operate in China.

Left without Bing’s help, Chinese Internet users are forced to use local search engines, like Baidu, that aggressively filter websites and don’t provide the same level of relevance found in U.S. search engines.

It’s unclear what happens from here. If the ban is indeed a technical flaw, then Bing could be back up soon in China. If not, the ban could be indefinite.