In an update Thursday, the platform said hackers were able to gain control of a small number of those accounts and send tweets from them.
The company added that it was continuing to assess whether hackers were able to access private data of the targeted accounts.
“We have also been taking aggressive steps to secure our systems while our investigations are ongoing,” Twitter said. “We’re still in the process of assessing longer-term steps that we may take and will share more details as soon as we can.”
U.S. Democratic presidential candidate Joe Biden, former U.S. president Barack Obama and rapper Kanye West were among those whose accounts were hacked during the attack.
Other accounts included ones belonging to Tesla founder Elon Musk, Amazon founder Jeff Bezos, billionaire and former New York City mayor Michael Bloomberg and Microsoft co-founder Bill Gates.
The affected Twitter accounts shared tweets asking for bitcoin donations. Most of the tweets were deleted shortly after they were posted.
Twitter reiterated that it was working with impacted account owners.
White House Press Secretary Kayleigh McEnany said Thursday that President Donald Trump’s account remained secure and “was not jeopardized.”
The FBI’s San Francisco division is leading an inquiry into the Twitter hacking, it said in a statement on Thursday, as more Washington lawmakers called for an accounting of how it happened.
“This hack bodes ill for November balloting,” U.S. Senator Richard Blumenthal, a Democrat, said in a statement scolding Twitter for “its repeated security lapses and failure to safeguard accounts.”
“So many security red flags are raised by this criminal attack that the culprits should be tracked down as quickly as possible,” he said.
U.S. Rep. Josh Hawley wrote to Twitter and its CEO Jack Dorsey during the hack calling for the company to work with the FBI and Department of Justice to secure its platform, and then answer questions publicly about the effects of the breach.
Reuters reported the U.S. House Intelligence Committee was in touch with Twitter regarding the hack, according to a committee official who did not wish to be named.
In an extraordinary step, Twitter temporarily prevented many verified accounts from publishing messages as it investigated the breach.
Twitter said Thursday it will continue disabling data downloads for all accounts as its investigation into the hack continues.
In 2010, Twitter reached a settlement with the U.S. Federal Trade Commission after it was found the company had lied about efforts to protect users’ information during an extended hack the year before.
Under the terms of the settlement, Twitter was barred for 20 years from misleading users about how it protects the security and confidentiality of private information.
Twitter‘s shares fell a little over 1 per cent on Thursday.
—With files from Reuters