The wreckage of an Airbus A-310 plane sits smoldering after crashing in the Siberian city of Irkutsk, Russia, early Sunday July 9, 2006

Russian President Vladimir Putin has declared Monday a day of national mourning for the more than 120 people killed when a Russian plane crashed in the Siberian city of Irkutsk.  More than 60 people survived the fiery crash.

Russian Presidential envoy Anatoly Kvashnin says Sunday's air crash was a horrible tragedy, and that the top priority now is to help save the dozens of people who were badly burned and injured.

The Russian passenger plane, operated by Sibir airlines, skidded off a wet runway in the city of Irkutsk as it was landing and burst into flames.  The Airbus A-310 was  carrying more than 200 people, including several children on their way to a summer camp holiday.

Kvashnin, the presidential envoy, says investigators believe mechanical error is the most likely cause of the crash, but human error has not been ruled out.

Transport Minister Igor Levitin says the wet runway may have played a part. 

Upon reaching the end of the runway, the plane reportedly careened into a concrete barrier, bursting into flames.  It then continued to travel through a nearby one-story car garage, before stopping in close proximity to neighboring houses.

Firefighters battled smoke and flames for well over two hours before securing the site for search and rescue.

Russian television broadcast images of worried loved ones returning to Moscow's Domodedovo airport, from which the flight originated.  There, officials set up an emergency command center to provide information and comfort to family members.

Both of the plane's black boxes have been recovered and handed over to regional prosecutors, who will study them for further clues into the cause of the crash.

Flags will be flown at half-staff Monday, and all televised entertainment programs have been canceled.

Two months ago, another air crash involving an Airbus plane killed 113 people in the Russian Black Sea resort of Sochi.