More than half the population of Nagorno-Karabakh has fled the breakaway region recently reclaimed by Azerbaijan, creating a mass exodus of ethnic Armenians.

The migration began Sunday. By Thursday evening, over 78,300 people — more than 65% of the population of 120,000 — had left for Armenia, and the influx continued unabated, according to Armenian officials.

The surge of families on the move could be seen on the only road to Armenia. It quickly filled with vehicles, triggering a massive traffic jam. Long lines of cars that were packed to the roof with belongings snaked slowly through the mountains.

A student reported that it took three days to get to Armenia from the regional capital of Stepanakert, a distance of about 50 miles (80 kilometers).

Azerbaijani authorities have pledged to respect the rights of ethnic Armenians, but tens of thousands of Nagorno-Karabakh’s residents feared reprisals.

In three decades of conflict between the two countries, each has accused the other of targeted attacks, massacres and other atrocities, leaving people on both sides deeply suspicious and fearful of the other.

Nagorno-Karabakh was internationally recognized as part of Azerbaijan’s sovereign territory. Azerbaijan carried out a lightning offensive last week and demanded that Armenian troops in Nagorno-Karabakh disarm and the separatist government disband.