Deadly clashes broke out on Tuesday between DR Congo troops and an armed group at an empty UN base in the country's troubled east, officials said.
Two attackers were killed and four captured when the group struck the site in the city of Butembo, mayor Roger Mowa said.
The UN peacekeeping force in Democratic Republic of Congo (DRC) had moved its troops out of the base following violent protests in late July.
They were redeployed to outside the city, according to the authorities.
The attackers "thought that we had lied, that the MONUSCO troops hadn't left," said Mowa.
"They went and attacked this base and fortunately they didn't find anything there."
The city is "secure," he added.
Anti-UN protests broke out in North Kivu province last month, centered on Goma and Butembo. By (AFP)
UN bases in eastern DRC were assailed last month by protesters angered at MONUSCO's perceived failure to provide security.
Thirty-two demonstrators and four UN troops died over the course of a week-long disturbance, according to a Congolese toll.
An estimated 120 armed groups roam eastern DRC, many of them a legacy of two regional wars that flared in the last decade of the 20th century.
Among the most notorious are the Allied Democratic Forces (ADF), which the self-described Islamic State claims as its regional affiliate, and the M23, whose resurgence has parked a diplomatic row between the DRC and neighbouring Rwanda.
Last Thursday the DRC authorities said MONUSCO had "already left" Butembo and that any remaining equipment in the city would be moved out.
But MONUSCO then insisted that it was "not leaving Butembo" but "momentarily suspending its operations."
The city authorities published what they called a timetable for MONUSCO's "planned redeployment" in Butembo, with traffic movements scheduled from August 20 to 24.
The force's acting spokesman, Ndeye Khady Lo, told AFP on Tuesday that MONUSCO's "temporary redeployment has taken effect. We no longer have personnel, either civilian or military in Butembo."
The force's three bases were being secured by the DRC police and army, she added.
MONUSCO "will resume its activities in Butembo as soon as the minimum conditions guaranteeing safety and security for its personnel are there," she said.
The UN first deployed an observer mission to eastern Congo in 1999.
It became the peacekeeping mission MONUSCO -- the United Nations Organization Stabilization Mission in the Democratic Republic of the Congo -- in 2010, with a mandate to conduct offensive operations.
It has a current strength of about 16,000 uniformed personnel.
On August 9, more than 800 inmates escaped from Butembo's central jail after gunmen staged a jailbreak in which two policemen were killed.
A respected US-based monitor, the Kivu Security Tracker (KST), said the suspects were the ADF.