KABUL, Aug 19 (Reuters) - Several people were killed on Thursday in the Afghan city of Asadabad when Taliban fighters fired on people waving the national flag at an Independence Day rally, a witness said. It was not clear if the casualties came from the firing or from a stampede it triggered, witness Mohammed Salim said from the eastern city, the capital of Kunar province. A Taliban spokesman was not immediately available for comment. Reporting by Kabul bureau Editing by Robert Birsel Our Standards: The Thomson Reuters Trust Principles.