NEW YORK (AP) — A tweet containing computer code has started propagating itself through Twitter by taking advantage of a security flaw in Twitter's TweetDeck application.

In response, Twitter shut down the application's access to tweets.

The tweet is automatically "retweeted," or sent out again, when processed by TweetDeck. Affected tweeters saw pop-up windows on their screens. The tweet was retweeted tens of thousands of times Wednesday.

Twitter, which owns TweetDeck, initially told TweetDeck users to log out and log back in. When that proved ineffective, it shut down the application's access to tweets.

It's not the first time tweets containing JavaScript code have self-propagated through security holes in Twitter. The last major outbreak was in 2010.