Insurgents breached Syria’s largest city on 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.

Syrian rebels have entered the country’s second city of Aleppo, after launching a dramatic surprise attack on the government-held areas of northern Aleppo province earlier this week. The development is significant: not only was Aleppo previously seen as very well defended,

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.