Grozny, the capital city of the southern Russian republic Chechnya before it made an emergency landing approximately 3 kilometers (1.8 miles) from Aktau, Kazakhstan, the carrier said on Wednesday.

Russian state media reported that the plane was rerouted due to heavy fog in Grozny.

According to flight-tracking website Flightradar24, the plane set off on Wednesday at 7:55 a.m. Azerbaijan Standard Time (10:55 p.m. Tuesday ET) and crashed at 10:28 a.m. Azerbaijan Standard Time (1:28 a.m. Wednesday ET).

Officials did not immediately explain why the plane had crossed the Caspian Sea, when Baku and Grozny are to its west and Aktau is to its east.

Kazakhstan’s Minister of Transport, Marat Karabayev, said Thursday that a Kazakh control center received a signal from Russia around 45 minutes before the plane crashed, saying that the flight was being diverted.

The Russian dispatcher said that the aircraft was experiencing a failure in its control systems, and that the crew decided to fly to Aktau after receiving reports of bad weather, Karabayev said. The dispatcher later said that an “oxygen tank exploded in the passenger cabin, causing passengers to lose consciousness,” according to Karabayev.

While the Azerbaijan Airlines crew made two landing approaches at Aktau airport, the aircraft deviated from its course, and lost communication with Aktau dispatchers when it crashed, Karabayev said.

Flightradar24 said in a social media post that the aircraft was “exposed to GPS jamming and spoofing near Grozny.” GPS jamming can significantly hinder a plane’s ability to navigate and communicate, Flightradar24 said, creating potential safety risks.

Data and video of the crash also “indicate possible control issues with the aircraft,” Flightradar24 said.