An attack was reported on the headquarters of the G5 Sahel Joint Force in the Mopti region of Mali on Friday, June 29.

There were a number of reports of a large explosion followed by gunfire, which lasted for at least an hour.

It was unclear who was responsible for the attack, the extent of it, and the number of casualties.

A hospital source said six people were killed, AFP reported.

“We transported the bodies and the injured to the hospital, but we don’t know whether some of the injured have died in hospital. There are six dead on the ground,” a military source told AFP.

Mali’s defense minister reportedly said the base in Sevare was attacked with rockets and followed by an attempted infiltration. The minister later said that a vehicle bomb was also used in the attack.

A Senagalese quick reaction force reportedly deployed to the base.

A suicide bomber tried to storm the base, AFP reported citing a security source. A witness, identified as Haoussa Haidara, said “there was a huge blast” followed by gunfire.

Other reports said that the source of the explosion was a suicide vehicle bomb.

The attack comes just days after an investigation carried out by the U.N. mission in Mali concluded that Mali soldiers executed 12 civilians in Boulikessi in May.

It is also three days before a planned meeting of the heads of the G5 Sahel states with French President Emmanuel Macron to discuss progress made by the force.

The G5 Sahel, comprised of Burkina Faso, Chad, Mali, Mauritania and Niger, was launched in 2014 to improve cooperation on development and security in West Africa.

They launched the G5 Sahel joint counter-terrorism force in July 2017. Its mandate is to combat terrorism, transnational organized crime and human trafficking in the Sahel area.

The five nations aim to deploy 5,000 troops in the region along the southern edge of the Sahara desert to work alongside thousands of troops deployed to France’s Operation Barkhane in the wider Sahel and the U.N.’s Minusma peacekeeping mission in Mali.

Last month Niger’s defense minister said the force was ready to launch operations, but a push by France and U.N. Secretary-General Antonio Guterres for direct funding was rejected by the United States at the Security Council.

On June 13, the European Union’s diplomatic chief Federica Mogherini proposed a new €10.5 billion ($12.4 billion) European Peace Facility that could pay for military equipment for partners in crisis zones such as Africa’s Sahel region, including the G5 Sahel Joint Force.