TIJUANA, Mexico, April 29 (Reuters) - Mexico's government sent more than 3,000 soldiers and federal police to Tijuana on Tuesday, stepping up a war against violent drug smugglers after 17 gunmen were killed in a street battle between cartels.

The several thousand troops and federal police already deployed by President Felipe Calderon to beef up security in Tijuana, across the border from San Diego, have been unable to stop feuding drug gangs.

In one of the deadliest episodes in Mexico's three-year drug war, a shootout between gunmen from rival factions of the Arellano Felix cartel on Saturday left bodies and bullet casings scattered along a road in the city.

Calderon has sent some 25,000 soldiers and federal police to fight drug cartels near the U.S. border and in other hot spots across Mexico but violence has continued, increasing in some regions.

Some 190 people have been killed in Tijuana so far this year. In 2007, there were more than 2,500 drug killings across Mexico and there have been more than 900 this year.

The Arellano Felix gang was long the dominant trafficking organization in Tijuana, smuggling drugs into California. Recently the group has been under attack from a rival gang from the Pacific state of Sinaloa, led by Mexico's most wanted man, Joaquin "Shorty" Guzman. (Reporting by Lizbeth Diaz; Editing by Eric Beech)

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