KABUL—Protests against the Taliban’s takeover in Afghanistan spread to more cities on Thursday, including the capital Kabul, and a witness said several people were killed when the terrorists fired on a crowd in Asadabad in the eastern province of Kunar. “Our flag, our identity,” a crowd of men and women waving black, red, and green national flags shouted in Kabul, a video posted on social media showed, on the day Afghanistan celebrates independence from British control in 1919. A witness reported gunshots near the rally, but they appeared to be Taliban firing into the air. Marchers chanted “God is greatest.” At some protests elsewhere, media have reported people tearing down the white flag of the Taliban. A Taliban spokesman was not immediately available for comment. Some demonstrations are small, but combined with a scramble by thousands of people to flee the country via Kabul airport they underline the challenge the …