A joint operation by Democratic Republic of Congo government troops and UN peacekeepers has seized control of Mbandaka airport from a local militia.
The airport in the north-western Equateur province was overrun on Sunday in clashes which led to the deaths of two UN workers and several civilians.
But some fighters are reported to be still at large so government and UN troops are trying to hunt them down.
Two rival ethnic groups have been fighting for local fishing rights.
This dispute is entirely separate from the unrest involving numerous armed groups in eastern DR Congo, which has drawn the world's biggest peacekeeping operation to the country.
Mbandaka is the capital of Equateur province, where at least 100 people were killed in clashes between the Lobala and Boba communities last year, displacing an estimated 200,000 people.
Between 30 and 100 fighters were believed to have been part of Sunday's attack.
UN radio reports that a local hospital received 14 bodies on Monday, according to the AP news agency.
Soldiers are now patrolling in town and most shops remain closed.
A local resident in Mbandaka told the BBC's Thomas Fessy in Kinshasa that many people were scared and were staying at home.
A UN spokesman in Kinshasa, Madnodje Mounoubai, told Reuters news agency it was thought the rebels were from the Enyele community - a Lobala sub-tribe.
The UN is in talks with DR Congo officials on withdrawing its 20,500-strong peacekeeping mission, Monuc.
The mission's current mandate expires in May.
Our correspondent says this new fighting might put such a withdrawal into question.