(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.
Russia's Investigative Committee has launched a criminal case over the crash, committee spokeswoman Svetlana Petrenko told Tass.
The Russian government has not always been forthcoming about casualties in Syria.
Although the identity of a pilot shot down in northwest Syria last month was announced by the government, officials have been reticent to discuss the death and injury in early February of dozens of Russian military contractors in US airstrikes in Syria.
Tuesday's crash was not the deadliest air incident related to Russia's military intervention in Syria.
In December 2016, a Tupolev Tu-154 aircraft crashed after taking off from the Adler airport near the Black Sea resort city of Sochi, killing 84 passengers and eight crew members. The plane was carrying more than 60 members of the Alexandrov Ensemble, the Russian army's official dance and choir company, on its way to Syria to give a holiday performance for troops.
Hmeimin, which is near Latakia, about 241 kilometers (150 miles) north of Damascus, is Russia's largest air base in Syria.
Putin visited Hmeimin in December, using the opportunity to meet with his Syrian counterpart, Bashar al-Assad.
Russia is a key ally of Assad, and its intervention -- with troops and weaponry -- in Syria's long civil war has helped tilt the balance in the Syrian regime's favor.