Missy Franklin (L) of the US and Italy's Federica Pellegrini are seen underwater as they swim in the women's 200m freestyle final during the World Swimming Championships at the Sant Jordi arena in Barcelona, July 31, 2013. [Photo/Agencies]

BARCELONA, Spain - American Missy Franklin, known as 'Missile Missy', won gold medal in women's 200 meters freestyle at the Barcelona FINA World Championships in which was the first time the US won in this discipline since 1978.

The 18-year-old Franklin was born in California although her parents are from Canada.

Franklin won five medals at the 2012 London Olympics, where she made her debut as she could not qualify for Beijing 2008. In London Franklin was the most successful female swimmer winning four gold medals and one bronze.

After that she won her first international medal in the 2010 FINA Short Course World championships in Dubai when she got silver in the 200 meters backstroke discipline.

In Shanghai 2011 she won a total of five medals, including three gold (in 200 meters backstroke, 4x200 freestyle and 4x100 Individual Medley), one silver (4x100 freestyle) and one bronze ( 50 meters backstroke).

Franklin told reporters in Barcelona she was "extremely happy" after winning three gold medals. She explained she trained a lot, but not only physically but mentally. "I focused on my own race and not on others around me".

Gold medallist Missy Franklin (L) of the US poses with bronze medallist Camille Muffat of France at the women's 200m freestyle victory ceremony during the World Swimming Championships at the Sant Jordi arena in Barcelona, July 31, 2013. [Photo/Agencies]

Franklin pointed out she "was not surprised to see Federica Pellegrini on the podium".

The 24-year-old Italian Pellegrini, who had won gold medal in Rome 2009 and 2011 while finishing fifth in London 2012 took silver on Wednesday.

"I am very happy and I did not expected to be on the podium this year", said Pellegrini, while pointing out she had practiced only backstroke before coming to Barcelona so "I did not expect these results", she said.

Meanwhile, France's Camille Muffat, who had set an Olympic record in London in 400 meters freestyle clocking 4:01.45, won bronze medal.