The apparent terrorist attack on the Boston Marathon has intensified the recent 'run for cover' on world stock markets.
There had already been a rush to dump gold before the blasts while oil took a fresh tumble amid an earlier world sell-off on fears of slowing economic recovery.
The Dow Jones closed 1.8% lower while Asian markets also lost value overnight as commodity stocks fell. European markets also opened lower.
The effect of the attack on Boston, while seen to be a temporary shock, added to the gloom as fears grew that an end was in sight for Federal Reserve support for the US economic recovery.
The sell-off in markets was triggered by the Chinese government's report on Monday that annualised growth in the world's second-largest economy slowed to 7.7% in the first quarter from 7.9% in the final quarter of last year.
Growth was expected to accelerate slightly to 8%.
Gold endured its sharpest drop in price over two days since 1983 on Monday, with the cost of a troy ounce falling to $1,350 before recovering slightly early on Tuesday.
Brent crude oil tumbled below $100 a barrel overnight as weaker Chinese growth was seen as hitting demand.
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