An official from the Department of Defense has acknowledged that a Sunday airstrike aimed at al-Qaeda targets inside a compound in Afghanistan’s southern Helmand province may have also killed civilians, The Washington Post reports. The official, who is in Kabul, Afghanistan, and spoke on the condition of anonymity, said the airstrike came after a prolonged firefight between American and Afghan ground forces and the suspected al-Qaeda targets. According to the official, the airstrike was called after the exchange of fire continued from late Sunday night into early Monday morning, and troops were still unable to move into the compound.

U.S. officials have said the strike was ordered “against barricaded terrorists firing on Afghan and U.S. forces,” and that “the majority of those killed in the fighting died from al-Qaeda weapons or in the explosion of the terrorists’ explosives caches or suicide vests,” according to a statement from the command overseeing all U.S. forces in Afghanistan. Some local Afghan officials, however, have reported that 40 civilians were killed while attending a wedding, and that the official number is still unknown because cellphones are not working in the area. Afghanistan’s defense ministry is reportedly investigating the reports of civilian deaths.