The Algerian defense ministry says over 257 people have died after a military plane crashed in northern Algeria, BBC reports.

It happened shortly after the Ilyushin II-76 aircraft took off from Boufarik military airport near Algiers this morning. The plane was traveling to Bechar in southwest Algeria.

Although authorities are working to identify the remains of those killed, army personnel and their families are among the dead, along with 10 crew members, BBC says. The army's chief of staff has ordered an investigation into the crash, as the cause has yet to be determined.

26 members of the Polisario Front are also among the dead—the political and military organization seeks independence from Morocco for Western Sahara and is supported by Algeria.

This incident is the deadliest plane crash since 2014, when 298 people on the Malaysian Airlines flight MH17 died when it was shot down over eastern Ukraine. It's also the second deadliest crash since 2003.