A crowd in Algeria beat to death a man they accused of involvement in setting deadly fires that the president said were largely the work of arsonists. At least 90 people have died in fires that broke out on Monday, mainly in the North African country's Kabylie region. Algeria's state prosecutor said it was investigating the lynching in Larbaa Nath Irathen, in the Tizi Ouzou district, one of the worst hit by the fires. Video footage posted online on Wednesday showed a crowd beating to death Jamal Ben Ismail, 38, and setting him on fire. The state prosecutor said those responsible "will receive a severe punishment", and that "odious crimes should not remain unpunished". The Algerian League for the Defence of Human Rights branded the killing as "barbaric and atrocious". "Scenes of the lynching and torching of the suspected arsonist – a young artist who had come to help put out the fires – are shocking," the Algerian group said. Ben Ismail's father, quoted by local media, called for calm as he urged the authorities to "shed light" on his son's death. President Abdelmadjid Tebboune said on Thursday that 22 people had been arrested on suspicion of starting the fires. "Some fires have been caused by high temperatures but criminal hands were behind most of them," Mr Tebboune said in a televised speech. "We have arrested 22 suspects, including 11 in Tizi Ouzou. Justice will perform its duty." Algeria on Thursday began observing a three-day mourning period for those killed in the fires. The dead include 33 soldiers the army sent to help firefighters contain the fires. "It's a disaster ... disaster. But our strength will not collapse," Mr Tebboune said, praising aid caravans from other provinces to provide affected regions with food, medicine and other donated material. "We must preserve national unity ... I insist on national unity," he said. As well as sending soldiers, the army has been using six helicopters to extinguish blazes. They are supported by two firefighting planes hired from the European Union and which have been in action since early on Thursday. Two more planes will arrive from Spain on Friday and a third one from Switzerland in the next three days, Mr Tebboune said. The fire service said its teams were still fighting 29 fires across 13 provinces, mostly in coastal regions east of the capital Algiers, with aircraft carrying out hundreds of missions to drop water on the fires. Almost 7,500 firefighters, backed by planes from France and Spain as well Russian helicopters operated by the army, have managed to put out over 40 blazes in 24 hours. The fires broke out amid record high temperatures in the Mediterranean region where other countries are also fighting wide-ranging fires, including neighbouring Tunisia, Italy, Greece and Turkey. <br/>