An Algerian military plane has crashed near the capital killing 257 people on board, officials say.
The aircraft came down just after taking off from Boufarik military airport, west of Algiers.
An investigation into the cause is under way. Algerian President Abdelaziz Bouteflika has declared three days of national mourning.
Most of the dead are army personnel and their families, the defence ministry says. Ten crew members also died.
Passengers from Western Sahara, a disputed territory annexed by Morocco after Spain withdrew in 1975, were among the fatalities.
The Polisario Front, which is seeking independence for the territory and is backed by Algeria, says 30 Western Saharans, including women and children, died. A senior member of Algeria's ruling FLN party said those killed included 26 Polisario members.
The plane, an Ilyushin Il-76, was travelling to Bechar and Tindouf in the south-west of the country. The Tindouf region, which borders Western Sahara, is home to refugee camps and serves as a base for the Polisario Front.
Wednesday's plane crash is the deadliest in the world since July 2014, when all 298 people on board Malaysian Airlines flight MH17 died when it was shot down over eastern Ukraine.
It is also the second-deadliest plane crash since 2003.
The authorities are working to identify remains of those killed. Footage from the scene shows smoke coming off wreckage in a field.
This is not the first major plane disaster in Algeria.
Four years ago a plane carrying military personnel and family members crashed in Algeria, killing 77 people.