BEIRUT (AP) — Insurgents breached Syria’s largest city Friday and clashed with government forces for the first time since 2016, according to a war monitor and fighters, in a surprise attack that sent residents fleeing and added fresh uncertainty to a region reeling from multiple wars.

The lightning assault on Aleppo by the Islamist militant group Hayat Tahrir al-Sham abruptly redrew the front lines of Syria’s civil war.

Insurgents have breached Syria’s second-largest city, Aleppo, clashing with government forces, according to a Syria war monitor and fighters.