Hackers hijacked the Twitter account for The Associated Press on Tuesday and sent out an erroneous message reporting explosions at the White House that injured President Barack Obama.

Within minutes, Jay Carney, Mr. Obama’s press secretary, confirmed that the President was unharmed, and Julie Pace, the chief White House correspondent for the AP, announced at a White House briefing that the account had been hacked.

Twitter suspended the account but by then the post had already moved markets. The Dow Jones industrial average plummeted more than 150 points, then surged back after it became clear there had been no incident.

A group calling itself the Syrian Electronic Army claimed responsibility for the attack.

The group’s Twitter account is linked to the website Syrianelectronicarmy.com, an Arabic language site that broadcasts what the group says are its latest computer attacks. — New York Times News Service

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