Over the course of 100 days in 1994, between 7 April and mid-July, up to a million people were killed in Rwanda, in a mass slaughter unparalleled in modern history.

It is believed that 800,000 people were killed in the first six weeks, at a rate five times higher than that of the Nazi Holocaust. Around one-fifth of the country's entire population was murdered. Most of the dead were Tutsis, and most of the killers were Hutus. This was genocide; a concerted effort to exterminate an entire group of people.

Rwanda genocide
Shelves of skulls are pictured at one of the many genocide memorials in Rwanda Reuters

The Tutsi minority were ruling caste, historically in control of the monarchy, the army and the administration. Resentment boiled over among Hutus, who made up 84% of Rwanda's population. In 1990, rebels of the Tutsi-dominated Rwanda Patriotic Front (RPF) invaded northern Rwanda from neighbouring Uganda.

The RPF's success prompted President Juvenal Habyarimana, a Hutu, to sign a deal with them to end years of civil war and allow power sharing. However, Habyarimana was slow in implementing the plan and a transitional government failed to take off.

Rwanda genocide
A Rwanda Patriotic Front (RPF) rebel soldier stares at a portrait of slain president Juvenal Habyarimana in Kigali Corinne Dufka/Reuters

On 6 April 1994, a plane carrying Habyarimana and Burundi's President Cyprien Ntaryamira was shot down in a rocket attack. Habyarimana's death triggered a 100-day orgy of violence, perpetrated mainly by Hutus against Tutsis and moderate Hutus. Hundreds of thousands of people were slaughtered by hand, using home-made weapons and household tools – knives, hammers and machetes. Tutsi families were blown up in churches where they had taken refuge.

Finally in July, the RPF – under the command of Paul Kagame – captured Kigali, and around two million Hutus fled to Zaire (now the Democratic Republic of Congo). Thousands of these refugees, who included those who carried out the massacres, died of dehydration and cholera.

The West largely stood by and ignored what was happening. When diplomatic messages warned the US, Britain and the United Nations of an imminent "new bloodbath" in February 1994, no action was taken. The UN finally agreed to increase its contingent of troops to 5,000, but they weren't deployed until after the killing had stopped.

IBTimes UK presents this harrowing series of photos illustrating the darkest days in recent history.

Rwanda genocide
8 May 1994: Dead bodies lie along the side of a road about 70 kilometres north of the Rwanda/Tanzania border Corinne Dufka/Reuters
Rwanda genocide
23 July 1994: A dying Rwandan woman tries to breastfeed her child next to hundreds of corpses waiting to be buried at a mass grave near the Munigi refugee camp in Zaire, where thousands of refugees succumbed to cholera or dehydration Corinne Dufka/Reuters
Rwanda genocide
26 July 1994: A little girl suffering from cholera is carried past the bodies of hundreds of Rwandans in the Mugunga camp in Zaire Corinne Dufka/Reuters

Every year, on 7 April, millions of people in Rwanda hold events to pay homage to the victims of genocide.