A Russian warplane veered off a runway at the country's air base in Syria and suffered damage, killing its crew, the Defense Ministry in Moscow said.
The Sukhoi Su-24 jet was taking off from the Hmeymim air base on a combat mission when it went off the runway and "was destroyed," state-run news agency TASS and other Russian media quoted the ministry as saying.
"The airplane's crew was unable to eject and died," the ministry said, adding that a technical problem was one possible cause of the crash.
The Su-24 normally has a crew of two.
Moscow has given President Bashar al-Assad's government crucial military and diplomatic support throughout the more than six-year war in Syria, which began with a crackdown on pro-democracy protesters.
Russia began a campaign of air strikes in support of Assad's government in September 2015 and has also stepped up its military presence on the ground in the Middle Eastern country.