Russia's Ministry of Emergency Situations announced on Sunday that a Boeing 737 had exploded when trying to land in the central city of Kazan on the Volga River.

The plane, which had taken off from Moscow, "crashed at Kazan airport at 7:25 p.m. (1525 UTC)," the ministry's local branch said in a statement.

Flight U363 was operated by the regional Tatarstan Airlines, early indications suggested that nobody survived the crash.

"According to preliminary information, all the people on board the flight - 44 passengers and six crew members - were killed," a ministry spokeswoman told the AFP news agency, issuing similar statements elsewhere.

Kazan, roughly 800 kilometers (500 miles) east of Moscow, is the capital of the oil-rich region of Tatarstan.

There were no immediate indications of what caused the crash, but local news agencies reported that the plane made at least two attempts to land before the accident. Russia has seen several fatal air crashes in recent years, often involving small regional carriers. Officials frequently blame such incidents on either pilot inexperience or poor maintenance of the planes.

msh/pfd (AFP, dpa)