On Thursday, Anonymous started to follow through on that promise, reportedly posting personal information about Trump online. Most of it was already public, like his birthday, his place of birth, and his legal counsel, but there were a few tidbits that had been private, namely his (alleged) social security number and the number to his cell phone, according to USA Today.

In saying it would target Trump, Anonymous cited the White House hopeful’s characterization of Mexicans as “rapists,” his mocking of a disabled reporter, and his insults against women as its motivation for cyberattacks. The group’s hackers often use distributed denial of service attacks—overwhelming floods of Internet traffic—to pummel computer servers.

The Anonymous YouTube page had asked participants to target the website “trumpchicago.com” on April 1, or April Fool’s Day in the U.S., but based on the information posted Thursday, it looks like the group got a head start.

When asked for comment, Trump spokeswoman Hope Hicks did not say whether the information posted online was legitimate but told Fortune in an email that “government and law enforcement authorities are seeking the arrest of the people responsible for attempting to illegally hack Mr. Trump’s accounts and telephone information.”

This story has been updated to reflect comments from the Trump campaign.