President John Magufuli said he was “deeply shocked and saddened” by the deaths, which come amid rising violence against civilians, the army and UN troops in the DRC's eastern borderlands.
Speaking at Independence Day celebrations in Dodoma yesterday, the president paid tribute to the fallen heroes for their ultimate sacrifice.
Magufuli called on Tanzanians to pray for victims and survivors of the deadliest single attack on a UN peacekeeping mission in 25 years.
The Minister for Defence and National Service, Dr Hussein Mwinyi, told The Guardian on Sunday that efforts were underway to bring back bodies of the Tanzanian soldiers slain in the attack.
United Nations Secretary-General Antonio Guterres expressed "outrage and utter heartbreak" and called the attack a war crime, urging Congolese authorities to swiftly investigate. The US State Department's Bureau of African Affairs said it was "horrified."
UN peacekeeping spokesman Nick Birnback said it was the deadliest attack on a UN peacekeeping mission since June 1993, when 22 Pakistani soldiers were killed in Somalia's capital, Mogadishu.
The peacekeepers killed on Thursday night were all from Tanzania. At least five Congolese soldiers were also killed in the attack that has been blamed on one of the region's deadliest rebel groups.
Three peacekeepers were missing, the UN said. More than 20 were evacuated for medical treatment in the regional capital, Goma.
Birnback, the UN peacekeeping spokesman, called the assault "a determined and well-coordinated attack by a well-armed group."
It was not clear when military reinforcements arrived after the attack, the UN said. Conditions in the region are "very, very challenging," said UN peacekeeping chief Jean-Pierre Lacroix, who said the attack followed a recent increase in activities by various armed groups. He called the assault a response to the UN mission's own "increasingly robust posture."
"We are disturbing them," he said. "They do not like it."
The UN peacekeeping base that came under attack is about 45 kilometers from the Congolese town of Beni, which has been repeatedly attacked by the Allied Democratic Forces (ADF) rebel group. The ADF is suspected of being behind Thursday's assault. The base is home to the UN mission's rapid intervention force, which has a rare mandate to go on the offensive against armed groups in the vast, mineral-rich region.
The UN mission in Congo is the largest and most expensive in the world. It has also been a high-profile target of the Donald Trump administration's cost-cutting efforts. The mission has a budget of $1.14 billion and over 16,500 soldiers. Nearly 300 peacekeepers have been killed since the mission arrived in 1999, according to UN data.
Members of the UN Security Council, which authorised the peacekeeping mission, stood in silent tribute to the victims at the start of a meeting Friday afternoon on a five-nation force in Africa's Sahel region.
Later, the council condemned the attack "in the strongest terms," underlined that deliberate attacks targeting peacekeepers may constitute war crimes, and called on Congo's government to ensure that the perpetrators "are swiftly brought to justice."
"This attack, the worst on UN peacekeepers in recent years, is a reminder of the extraordinary sacrifices made by these brave women and men every day," the council said.
Birnback said UN flags will fly at half-staff on Monday all over the world in memory of those killed or injured in the DRC.
Many rebel groups have come and gone during the UN mission's years of operation, at times invading the regional capital.
One of the greatest threats now comes from the ADF, which "has an agenda both ideological and extremist in nature, but also focused ... on exploitation of illegal resources," Lacroix said. He accused the rebels of preying on the local population.
The rebels once aimed to overthrow President Yoweri Museveni's regime in neighboring Uganda. By the 1990s, they had established themselves in Congo.
Human rights groups say at least 1,000 people have been killed in the last three years as the ADF intensified attacks in Congo. About a dozen rebels have been sentenced to death on charges related to participating in an insurrection movement.