A roadside bomb killed three coalition troops Friday during a patrol in Afghanistan's dangerous south, the U.S. coalition said.

The bomb attack happened in Uruzgan province. The coalition did not release any other information, including the troops' nationalities. U.S., Dutch and Australian troops operate in Uruzgan.

Taliban militants have increased their attacks the last three years and now control wide swaths of territory. President Barack Obama this week announced the deployment of 17,000 additional U.S. troops to bolster the 38,000 already in the country.