Afghan President Hamid Karzai abruptly ended a speech to a crowd of thousands after what sounded like gunshots rang out near Kabul's main stadium.
Officials urged the capacity crowd to remain calm, and said the loud noises Sunday were from stones thrown at a metal gate by people not able to get into the stadium.
Other reports say police fired shots in the air to keep the crowd from trying to force their way into the stadium.
U.S. military officials in Afghanistan say a coalition soldier was killed in a bombing Sunday in the southern province of Helmand.
A military statement says four other soldiers from the international force were wounded by the blast. The statement did not identify the soldiers' nationalities.
Early Saturday, two British soldiers serving with NATO's mission in Afghanistan were killed and several others wounded in a Taleban attack south of Garmsir in the same province.
The U.S. military also reports that U.S.-led coalition forces backed by war planes killed more than 30 suspected militants in the Garmsir area Saturday.
Some information for this report was provided by AFP, AP and Reuters.
