The Airbus A320 jet, on its way from Barcelona to Duesseldorf, came down near a ski resort in the Barcelonnette area in southeastern France, officials said.
"In light of the information available at the present time we cannot say whether there are survivors or how many there might be," Germanwings chief executive, Oliver Wagner, said in a brief statement on German television.
In late morning deals, Lufthansa's share price dived more than four per cent in Frankfurt.
Airbus shares sank 1.92 per cent to 58.85 euros (USD 64.43), also making it the heaviest faller in Paris.
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"Tragically, market movement cannot always been driven by pure stats," said Connor Campbell, analyst at Spreadex trading group.
"News that a Germanwings plane has crashed in the south of France caused a fall in (the share price of) Lufthansa... alongside Airbus, the plane's manufacturer," he told AFP.
European stock markets however were steady overall.
London's FTSE 100 index of leading shares was 0.01 per cent lower at 7,036.70 points.
"Very sad news and we have seen airline names drop on the back of this," said Guardian Stockbrokers analyst Atif Latif.
"The Airbus A320 is one of the most popular aircraft and (this incident) will question the safety aspect."
Shares in Air France-KLM were down 0.60 per cent at 7.60 euros (USD 8.31) in Paris, while British low-cost carrier easyJet fell 0.37 per cent to 1,861 pence.
Earlier today, Europe's main stock markets had fallen in the wake of disappointing Chinese manufacturing data.
Asian equity markets mostly turned lower after a gauge of Chinese manufacturing plunged to an 11-month low in March.
In foreign exchange activity today, the European single currency edged up to USD 1.0974 from USD 1.0945 late yesterday in New York.
The euro won a modest boost from hopes of a breakthrough in Greece's bailout talks with Germany.