Hundreds of ambulances and dozens of fire trucks with sirens wailing rushed to the scene of the crash, in an uninhabited area where one person was injured on the ground by debris. Firefighters extinguished the blaze and security forces set up a cordon to prevent journalists and onlookers from approaching.
Witnesses who had been working in nearby fields told AFP that the plane had burst into flames before it hit the ground. The defence ministry said in a statement that 247 passengers and 10 crew were killed without mentioning any survivors. Most of those on board were army members and their families, it said. There was no immediate word on the cause of the crash. Deputy Defence Minister General Ahmed Gaid Salah visited the site and ordered an investigation, the defence ministry said.
Algerian President Abdelaziz Bouteflika declared three days of national mourning over the crash starting Wednesday. The veteran leader also ordered that a special prayer be said for the victims after weekly Muslim prayers on Friday, a decree published by state press agency APS said. The Ilyushin IL-76 transport plane was bound for Tindouf in southwest Algeria near the borders with Morocco and Western Sahara.
The Tindouf region is home to refugees from Western Sahara and houses the administrative offices of the Sahrawi Arab Democratic Republic declared in 1976 by the Algiers-backed Polisario Front which seeks independence for the disputed region. Among the victims of the plane crash were 30 Sahrawis, "the sick and their companions, men, women and children, who had been returning from treatment in Algeria", said the Polisario. Rabat considers Western Sahara an integral part of Morocco and proposes autonomy for the resource-rich territory.
According to the plane manufacturer's website, the IL-76, a four-engine plane built in the Soviet Union and then Russia, can transport between 126 and 225 passengers depending on the model and configuration. The North African country has suffered a string of military and civilian aviation disasters but Wednesday's was Algeria's deadliest ever plane crash and the world's fourth costliest in human lives in 20 years.
Two Algerian military planes collided mid-flight in December 2012 during a training exercise in Tlemcen, in the far west of the country, killing the pilots of both planes. In February 2014, 77 people died when a military plane carrying army personnel and family members crashed between Tamanrasset in southern Algeria and the eastern city of Constantine. Only one person survived after the C-130 Hercules transport aircraft came down in the mountainous Oum El Bouaghi region.
The defence ministry blamed that crash on bad weather. An Air Algerie passenger plane flying from Burkina Faso to Algiers crashed in northern Mali in July 2014, killing all 116 people on board including 54 French nationals. In October the same year, a military plane crashed in the south of the country during a training exercise, killing the two men on board. That came more than a decade after all but one of the 103 people on an Air Algerie Boeing 737-200 died in March 2003 when it crashed on takeoff in the country's south after an engine caught fire.