(CNN) Thirty-nine people, including military personnel, were killed when a Russian transport plane crashed Tuesday while trying to land at Hmeimin air base in northwest Syria, Russian state media reported.

All 33 passengers and six crew members were killed in the crash, state-run RIA-Novosti reported, citing the Defense Ministry. Earlier, it had been reported that 32 people had died.

Russian President Vladimir Putin was briefed on the incident by Defense Minister Sergei Shoigu during a working visit to Russia's Sverdlovsk region, the Kremlin said in a statement.

The crash occurred as the Antonov-26 transport plane came down 500 meters (about 550 yards) short of the runway, the Defense Ministry said in a statement quoted by the state-run news agency, Tass.

The ministry said it was investigating the crash, adding that "preliminary data suggests it could be a technical malfunction." It also ruled out the possibility that the plane had been fired upon.

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