BEIRUT — Tens of thousands of terrified men, women and children streamed out on foot and in pickup trucks Thursday from besieged enclaves on two fronts, fleeing bombings from the Syrian military near Damascus and Turkish troops in the country’s north.

It was the largest single-day exodus of civilians from fighting in Syria’s civil war and a reminder of how the conflict that sparked the world’s worst humanitarian catastrophe continues to hit new lows as it enters its eighth year.

The flight of an estimated 42,000 civilians came as their attackers – Syrian government troops, backed by Russian aircraft, and Turkish forces – pushed their way into civilian centers, in strategic military advances that could turn the page on some of the most volatile flashpoints of the conflict.

Near Damascus, the Syrian government is chipping away at one of the largest and most significant opposition bastions since the early days of the rebellion – communities where some 400,000 people are estimated to be holed up.

Since mid-February, Syrian troops have targeted the capital’s sprawling eastern Ghouta region with shells, airstrikes and even toxic gas, according to opposition medics. They are now in control of the majority of the enclave that had been in rebel hands since 2012.

Over the weekend, Syrian troops divided the enclave into three sectors, isolating the major urban centers and enabling a swift advance.

Starting Wednesday night, intense shelling and aerial strikes paved the way for a ground advance on Hamouria, a town in the region’s isolated southern pocket. It also triggered a mass exodus, unexpected in scale.

At least 10,000 men, women and children emerged from Hamouria and nearby opposition towns.