Which of the following is CORRECT?

NATO and Afghan forces are investigating the incident in western Afghanistan that killed members of the country’s army and police.
    Earlier, NATO said 25 international and Afghan soldiers were wounded in the area. Officials initially blamed "insurgent activity" for the casualties, but later said it was possible the soldiers were hit by friendly fire.
    Afghanistan’s Interior Ministry spokesman Zamary Bashary tells VOA that this is a sad incident.
    He added that incidents such as this one are rare, especially after the United States imposed new restrictions on air strikes in an effort to avoid civilian casualties.
    The troops were conducting an operation to find two missing US soldiers who are believed to have drowned.
    Local police officials say the two soldiers were swept away Wednesday while trying to save supply boxes that fell into the water after being air-dropped.
    This year has been the deadliest for international troops in Afghanistan since the fall of the Taliban-led government in 2001.