A military aircraft crashed into a residential building in the port town of Yeysk in Russia's southwestern Krasnodar Krai region on Monday evening, according to local authorities.
Some 13 residents were killed in the mishap, Russian media quoted a Health Ministry spokesman as saying on Tuesday.
Yeysk is located on the Azov Sea coast near Russia's border with Ukraine. The town has around 90,000 inhabitants and is home to a Russian air base.
The Kremlin said President Vladimir Putin had been informed of the incident, and had ordered the health and emergency ministers to fly to the region. He ordered "all necessary assistance" to be given to those affected by the incident, Russian news agency TASS reported.
According to the state RIA news agency, Russia's Defense Ministry said a Su-34 bomber crashed and set off a fire spanning 2,000 square meters (21,526 square feet).
Several hours after the crash, Krasnodar Krai Governor Veniamin Kondratyev said emergency services had managed to put out the fire.
Deputy Governor Anna Minkova had initially said that three people had died and another 10 had been taken to hospital. The death toll was later revised to six, with six others missing.
On Tuesday, with search operations complete, the death toll stood at 13.
Russian news agencies cited emergency officials as saying that at least 19 people were injured. Some 250 residents of the building were evacuated, according to local emergency officials.
Kondratyev said the fire engulfed several floors of a nine-story building, affecting at least 17 apartments.
Kondratyev added his administration was "providing maximum assistance" to residents and promised to figure out the situation with the damaged apartments.