Local authorities said the incident occurred at around 4 pm when four male teenagers from Luong Son Commune went swimming in the Lam River.
While in the water, the group reportedly slipped into a deep section of the river and struggled to stay afloat.
Residents living near the scene noticed the emergency and rushed to help, successfully rescuing two of the teenagers.
The two missing youths were identified as Nguyen Van Thang, 17, and Tran Van Dai, 16.
By 9 pm, search and rescue teams, assisted by local residents, were continuing efforts to locate the missing teenagers through the night.
However, darkness and strong river currents were making the operation particularly challenging.
Nghe An Province has a dense network of rivers, lakes and reservoirs, many of which pose significant safety risks.
Local authorities record dozens of drowning incidents each year, most involving children and teenagers, particularly during the summer months.
