At least 15 people have been killed in an attack involving US-led forces in northwest Pakistan, intelligence officials and a witness said. The US-led coalition in Afghanistan said it had no immediate report of an incursion. Witness Habib Khan Wazir said the incident occurred after an US helicopter landed outside a home in the village of Musa Nikow in South Waziristan before dawn Wednesday. He said the troops came out and fired on people outside and inside a house. Pakistan's army said it was looking into the report. The US embassy declined comment.