At least six people have been singled out for their involvement in last month's Westgate mall attack –and that number is expected to double once the investigation is complete, a senior Kenyan government official said.

Previously, a spokesman for the Kenya Defense Forces identified four terrorists who took part in the mall attack, which left at least 67 people dead. Those four are Khattab al-Kene, an American Somali; Abu Baara al-Sudani, from Sudan; Omar Nabhan, from Kenya; and a man identified only as Umayr.

The senior government official said there was also a woman identified as Somali whose body was found with a mounted gun. The official said the woman was responsible for single-handedly killing more than 30 people.