In a rare rebuke of its own personnel, an internal inquiry ordered by United Nations Secretary-General Ban Ki-moon has found that members of a unit of the organization's peacekeepers committed a "grave violation" of UN policy when they fired on protestors in the Malian city of Gao in January, killing three people.

"Members of a MINUSMA Formed Police Unit used unauthorized and excessive force on civilian protestors during the demonstration," UN spokesperson Farhan Haq told reporters Thursday, referring to the acronym of the United Nations Multidimensional Integrated Stabilization Mission in Mali.

"The Secretary-General profoundly regrets the casualties among civilians resulting from the excessive use of force during this event," said Haq.

The inquiry reported that the peacekeepers were "left to face the protestors on their own," a situation that under their arrangement with Mali's government should have been dealt with by local troops. Investigators found that protesters hurled stones and Molotov cocktails, injuring five UN officers, and attempted to "breach the perimeter" of the UN's base in Gao. Still, the actions of a few of the peacekeepers, which left four wounded in addition to the three protesters that died, were deemed a serious breach of UN directives.

Haq said that the peacekeepers involved in the incident would be repatriated to their home country, where local authorities would be tasked with determining charges against them. The UN did not release the nationalities of the peacekeepers, but sources close to the investigation confirmed to VICE News on condition of anonymity that the blue helmets were from MINUSMA's Rwandan contingent.

Rwanda is one of the UN's largest troop contributors, providing more than 5600 blue helmets, according to UN figures. Their peacekeepers are often commended for being among the best trained.

"We've been in contact with the member state," said Haq. "We certainly want justice to be done in this case."

Speaking to reporters Thursday afternoon after he briefed the Security Council on the Mali report, UN peacekeeper chief Herve Ladsous said, "We regret profoundly the loss of lives and injuries that were caused by this," acknowledging that four peacekeepers "appear to have been directly implicated."

Knowledge that Rwandan troops were the ones involved appeared to be an open secret — if a secret at all — by the time of Ladsous' press conference. Asked specifically of what steps Rwanda would take, Ladsous only referred vaguely to "the relevant police contributing country," and said, "We trust that individuals responsible will be held fully accountable."

He added that UN officials had met this week with the families of the victims.

Though the UN will not make the internal report public, observers tentatively hailed its admission of the transgressions and MINUSMA's move to offer compensation to the victim's families.

"It's encouraging to see the UN own up to what its police did in Gao and pledge to compensate the victims, as well as make sure that UN staff are held to account," Philippe Bolopion, Human Right Watch's UN director, told VICE News.

However, Bolopion added that the move "will mean nothing if the country of origin does not provide proper justice, as has happened too often in the past."

Last year, a Jordanian peacekeeper was filmed shooting live rounds into a crowd of protestors in Haiti. An internal investigation of that incident was never released.

A separate internal UN report that was leaked last month outlined a culture of impunity at the UN when dealing with allegations of sexual abuse committed by peacekeepers.

"UN personnel in all missions we visited could point to numerous suspected or quite visible cases of SEA [sexual exploitation and abuse] that are not being counted or instigated," wrote investigators.

MINUSMA was launched in June 2013, following a French intervention that displaced extremists groups that had seized much of northern Mali after a military coup the year before. As of February 28, MINUSMA had 9,883 uniformed personnel.

The mission has been one of the UN's most deadly, with 46 deaths among its personnel resulting from skirmishes with al Qaeda linked groups, suicide bombings, and improvised explosive devices placed alongside highways. Nine Nigerien peacekeepers were killed last October near Gao when they were ambushed by jihadists on motorcycles.

Last month, militants opened fired with rockets and shells on a UN based in the town of Kidal in Mali's northeast, leaving one peacekeeper dead. The day before, a bomb exploded in a restaurant popular with Westerners in Mali's capital Bamako, killing five people. Among them was a Belgian security officer serving with the European Union in the country.