My An 1, which was carrying the clinker from the northern Quang Ninh Province to Ho Chi Minh City, was anchored near a buoy 12 km from Vung Tau, which borders HCMC, to clear a Covid-19 checkpoint at around 2:30 a.m. when the Lisa Auerbach rammed it.
The 138-meter ship was en route to Lotus port in Ho Chi Minh City, the Marine Administration of Vung Tau said.
All 17 people from the ship were rescued and taken on board by the Liberian ship.
The 15 people on the Lisa Auerbach were unharmed.
Authorities have marked the location of the sinking and issue maritime safety warnings. No oil spill had been detected as of Tuesday afternoon, and rescue forces are on standby in case a spill does occur.
The administration said the collision was an accident.
All people involved in the incident have been taken to Vung Tau for Covid-19 quarantine as a precaution.
An investigation has begun.