KABUL (AP) – An explosion in the center of the Afghan capital Sunday wounded at least 15 people, according to witnesses. It wasn’t immediately clear what caused the blast and no one immediately claimed responsibility.  Associated Press TV shows wounded being removed from the site, carried by passersby. Wais Ahmad, a money changer in the area, said the explosion happened inside a market where money changers operate. However, the market was closed at the time of the explosion. The blast was the first in the Afghan capital in months. Afghanistan’s Taliban rulers have stepped up security throughout most of the country since sweeping to power in August.