LOS ANGELES – In another sign that America’s auto industry is recovering from a deep downturn, Ford Motor Co. said Tuesday that it earned $2.1 billion in the first quarter of 2010.

The company was helped by a strong turnaround in its North American auto operations, which had an operating profit of almost $1.3 billion compared to a loss of nearly $665 million a year earlier.

Through the first quarter of this year, Ford’s F-series pickup truck was the best-selling vehicle in America and the only auto to cross the 100,000 sales barrier (103,359) year to date. Overall, Ford had three of the top 10 sellers, and its Focus compact car was No. 11.

The automaker sold 441,708 vehicles in the first quarter of 1010, according to Autodata Corp., up nearly 37 percent from a year ago and outpacing the industrywide gain of just under 16 percent during the same period. Its 17.4 percent market share is up almost three full percentage points from a year ago and trails only General Motors Co., according to Autodata.

International operations contributed to the quarterly profit with “all of our automotive segments reported an increase in sales compared with 2009,” said Ford Chief Executive Alan Mulally.

However, Mulally offered a word of caution, noting that the “recovery is fragile.”

The company’s sales rose 15 percent to $28.1 billion.

But the company is still working to pay down a mountain of debt accumulated from restructuring its operations prior to the recession and funding a union trust fund to pay retiree benefits.

“Ford was able to avoid a U.S. government bailout because they mortgaged the farm before the storm struck,” said James Bell, an analyst with auto information company Kelley Blue Book. “Ford’s success today is imperative to their ability to make full payments back to their lenders.”