Markets for stocks, bonds, oil and commodities were briefly roiled on Tuesday after a bogus report of explosions at the White House.

Shortly after 1 p.m. (1700 GMT), U.S. government debt prices surged briefly and stocks fell sharply after a false tweet from the Associated Press said there had been two explosions at the White House and that President Barack Obama had been injured.

An Associated Press spokesman told Reuters that an AP Twitter message reporting two explosions in the White House was “bogus.” The White House said Obama was fine.

U.S. stocks sharply cut gains briefly and then bounced back. The dollar pared gains against the yen, and the euro extended declines against the dollar.

“High-frequency traders cancel their orders on even one little tweet. They provide so much liquidity and don’t have obligations like market makers did in the past. We need other participants to make sure this kind of volatility doesn’t happen and we don’t [have them] anymore,” said Dennis Dick, proprietary trader at Bright Trading LLC in Las Vegas.

In the energy market, crude oil prices fell as much as 70 cents a barrel in a three-minute period following the Tweet, but just as quickly reversed those losses as it became clear the AP message was bogus.

Global equity markets resumed their upward trend, with Wall Street higher on strong corporate earnings.

The AP’s Twitter account was suspended shortly after the fake tweet. The news organization said the tweet came after hackers made repeated attempts to steal the passwords of AP journalists.