North American markets went for a wild ride Thursday amid fears of a growing European debt crisis and reports that one erroneous trade on the New York Stock Exchange might have triggered the sell-off.

Reports said the sudden drop was caused by a trader who mistyped an order to sell a large block of stock. The drop in that stock's price was enough to trigger "sell" orders across the market.

Traders gather on the floor of the New York Stock Exchange to watch one of the electronic boards that showed a steep decline in the markets Thursday. (Henny Ray Abrams/Associated Press)

The S&P/TSX composite index closed down 32.7 points to 11,842.43 while New York's Dow Jones industrials plunged 347.8 points to 10,520.32.

But earlier in the afternoon, investors briefly pushed the Dow down almost 1,000 points while the Toronto market lost as much as 452 points before recovering.

Nervous investors continued to pile into the perceived safe haven of the U.S. dollar, with the Canadian dollar closing down 2.08 cents to 95.03 cents US.

June oil fell $2.86 to $77.11 US a barrel, and now is down more than $10 from a high of $87.15 on Monday. June gold finished up $22.30 at $1,196.90 an ounce.

Elsewhere in New York, the Nasdaq composite index stepped back 82.65 points to 2,319.64, while the S&P 500 index fell 37.72 points to 1,128.15.

The drop came amid continuing concern among investors that an economic bailout package for debt-ridden Greece proposed by the European Union and the International Monetary Fund will not work, and the Greek crisis will spread to other high-debt European countries.

The euro dropped sharply even before the sell-off on North American markets after bond rating agency Moody's Investor Service said that Greece is not the only European country facing a debt crisis but that the banking systems in Portugal, Italy, Spain, Ireland and Britain could also be hurt by widening debt.

At the same time, Spain's borrowing costs rose at its debt auction Thursday as investors demanded higher rates from borrowers they see as riskier.

Late in the afternoon, the euro was down 1.75 cents to 1.2639 US, a drop of 1.4 per cent and its fourth decline in as many days.

'There's a lot of debt in the world, and investors don't like it.'—Peter Bethlenfalvy, DBRS

"What's happening is there's a lot of debt in the world, and investors don't like it," Peter Bethlenfalvy, co-president of ratings agency DBRS Ltd. in Toronto, told CBC News.

"With sovereign, household and corporate debt, you've got a triple threat, and investors don't like that.

“For the next decade, we're going to have a tough time growing GDP, as [large investors] are going to demand [debt be paid down]."

European Central Bank president Jean-Claude Trichet earlier Thursday told journalists its policymakers who met in Lisbon didn't discuss whether to buy eurozone government bonds on the open market.

Such purchases would help hold down borrowing costs for debt-strapped countries within the currency zone.

One portfolio manager blamed Thursday's market drop on European Central Bank president Jean-Claude Trichet, above, who, the manager said, failed to reassure markets about measures to support bank lending. (Francisco Seco/Associated Press)

Paul Ma, international portfolio manager with Calgary-based McLean and Partners, blamed Thursday's sell-off on Trichet.

"It started with the ECB doing nothing," he told CBC News. "Trichet, it's all his fault, really. So, people just gave up hope. They were hoping for some dramatic action ... but he didn't do anything, so the market sold off.

Ma, who has invested significantly in bets that the world economy will slow, said he expects the market sell-off will continue.

"It's not done yet," he said. "We're not even close to being done."

Andrew Busch, global currency and public policy strategist for BMO Capital Markets, also slammed the ECB for sitting on its hands and not dramatically increasing liquidity into the marketplace.

"The fact that they haven't already is astounding," he told CBC News.

With files from The Canadian Press and the Associated Press