An Afghan official says three South African nationals and one Afghan were killed in an attack on a guesthouse in the capital Kabul, revising the original toll up from one foreigner.

The chief of Kabul police, Gen. Mohammed Zahir, said Sunday that the head of an international aid group was killed, along with his son and daughter, in the attack the day before. He gave no ages for the children, and did not identify the organization.

Zahir said one of the three attackers wore a police uniform.

The attack was the second in as many days on guesthouses occupied by foreigners, and comes amid a spike in violence in the Afghan capital.

The U.S. and NATO formally end their 13-year combat mission in Afghanistan on Dec. 31.