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 fighting is a significant escalation since rebels launched a surprise offensive earlier this week, seizing towns and villages as they cut a path toward Syria’s second-largest city.

Syrian rebels against the country’s President Bashar Al-Assad advanced toward one of the largest cities in the country — the first time since 2016 — following a shock offensive launched by insurgents on Wednesday,