A fighter from Libyan forces allied with the U.N.-backed government moves through the neighborhood number three in Sirte to go into a front line fighting position with Islamic State militants, Libya September 22, 2016. REUTERS/Ismail Zitouny

Fighters from Libyan forces allied with the U.N.-backed government move through the neighborhood number three in Sirte to go into a front line fighting position with Islamic State militants, Libya September 22, 2016. REUTERS/Ismail Zitouny

A Libyan forces tank allied with the U.N.-backed government is seen during a battle with Islamic State militants in Sirte, Libya September 22, 2016. REUTERS/Ismail Zitouny

A Libyan forces tank allied with the U.N.-backed government is seen during a battle with Islamic State militants in Sirte September 22, 2016. REUTERS/Ismail Zitouny

A wounded fighter from Libyan forces allied with the U.N.-backed government, who was injured during a battle with Islamic State militants in Sirte, receives treatment in the field hospital in Sirte, Libya September 22, 2016. REUTERS/Ismail Zitouny

A fighter from Libyan forces allied with the U.N.-backed government holds a receipt left behind Islamic State militants in Sirte, Libya September 22, 2016. REUTERS/Ismail Zitouny

Fighters from Libyan forces allied with the U.N.-backed government take position during a battle with Islamic State militants in Sirte, Libya September 22, 2016. REUTERS/Ismail Zitouny

Fighters from Libyan forces allied with the U.N.-backed government take position as smoke rises during a battle with Islamic State militants in Sirte, Libya September 22, 2016. REUTERS/Ismail Zitouny