SAN FRANCISCO (AP) — Twitter CEO Jack Dorsey has found his official account hacked and sending racist and vulgar tweets to his 4.2 million followers.

The person tweeting from Dorsey’s account on Friday sent tweets such as “Hitler is innocent” and, using a vulgarity, asked “bald skeleton head,” referring to Dorsey, to unsuspend his account.

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Twitter says it’s investigating. The tweets were up for about 30 minutes before Twitter took them down. The company also suspended accounts that the hacker or hackers retweeted while they had control of Dorsey’s account.

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The incident comes as Twitter and Dorsey have promised to improve the “health” and civility of discourse on the social media service, cracking down on hate speech and abuse.

Twitter said around 2:20 p.m. that Dorsey’s account had been secured and that there was “no indication that Twitter’s systems have been compromised.”

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