A US military helicopter made an emergency landing in a mountainous region of Afghanistan at the weekend, injuring four special forces soldiers, the US military said on Monday. The chopper, a UH-60 Blackhawk, landed during combat operations in the troubled province of Uruzgan on Saturday, the military said in a statement. "In combat there are a lot of risks. Here in Afghanistan, we sometimes have to land on rocky, uneven terrain," the statement said.Three of the injured soldiers received immediate medical attention, while one was sent to a US medical facility for further treatment, it said, adding that an investigation had been launched.