Asian shares tumbled for a second straight day Tuesday following weak US and Chinese economic data, while traders were also spooked by a double bombing that hit the Boston Marathon. The weak China outlook hit commodity prices, with gold sinking to its lowest level since 2011 in New York after suffering its sharpest fall in 30 years, while on oil markets the Brent contract fell below $100 a barrel. Tokyo fell 1.06 percent by the break, Hong Kong lost 0.81 percent, Sydney eased 0.64 percent, Shanghai was 0.20 percent lower and Seoul shed 0.93 percent. Bangkok was closed for a public holiday. Global markets suffered a downturn on Monday after China released data showing growth in the world's number-two economy had slowed in the first quarter of the year, which was followed by weak US manufacturing figures. Asian markets ended Monday in the red and Wall Street's main indexes were already down when two explosions hit the Boston Marathon, one of the biggest sporting events in the US, killing at least three and injuring more than 100. "Markets are in the red on a knee-jerk reaction to the Boston bombing. It looks like the bears are at the gates," says Jonathan Ravelas, market strategist at BDO Unibank. As cities across the United States went on high alert President Barack Obama said it was not yet clear who was behind the blasts. While he did not say the blasts were a terror attack, a White House official said "any event with multiple explosive devices -- as this appears to be -- is clearly an act of terror". On Wall Street the Dow and S&P 500, which last week hit record highs, both slid. The Dow dived 1.79 percent and S&P 500 plunged 2.30 percent, while the tech-rich Nasdaq was 1.94 percent lower. The dollar bought 97.08 yen in early Asian trade, compared with 96.56 yen in New York Monday but well down from the 99.95 yen seen on Friday. The euro was at 126.60 yen and $1.3042, against 125.98 yen and $1.3048. The China results pummelled commodities, with gold at lows not seen since February 2011, while oil prices also sank, with Brent falling below $100 a barrel for the first time since mid-July. Gold plunged more than nine percent Monday to as low as $1,338.00 an ounce on worries over China's growth -- representing its worst dive since February 28, 1983. At 0315 GMT in Asia the precious metal was at $1,343.50 an ounce. Dealers have also been spooked by reports last week that Cyprus was preparing to liquidate some of its 14 tonnes of gold reserves to fund its part of a IMF-EU bailout plan. But the broader view is that with inflation expectations still flat -- as both US and Chinese data indicate -- people who buy gold as a hedge against rising prices have been driven to dump bullion. On oil markets Brent North Sea crude for May delivery shed $2.08 to $98.55. New York's main contract, light sweet crude for May, dropped $1.88 to $86.83. "You can't continue buying risky high-yield assets, which require growth ultimately, if the growth outlook is deteriorating," Greg Gibbs, senior foreign exchange strategist at the Royal Bank of Scotland in Singapore, told Dow Jones Newswires.