MOSCOW (AP) — A Russian warplane slammed into a residential building in the Siberian city of Irkutsk on Sunday, killing both crewmembers, authorities said. It was the second time in less than a week that a combat jet crashed in a residential area in Russia.

The Irkutsk region’s governor, Igor Kobzev, said the Su-30 fighter jet came down on a private, two-story building housing two families. He said that there were no casualties on the ground as the building’s five residents were out at the moment of the crash.

He said the residents would be offered temporary accommodation and compensation.

The cause of the crash wasn’t immediately known and an official probe has started. On Oct. 17, an Su-34 bomber crashed near an apartment building in the Sea of Azov port of Yeysk and exploded in a giant fireball, killing 15 and injuring another 19.

The crashes might reflect the growing strain that the fighting in Ukraine has put on the Russian air force.

The United Aircraft Corporation, a state-controlled conglomerate of Russian aircraft-making plants, said in a statement that the plane in Sunday’s incident came down during a training flight before its delivery to the air force. The jet carried no weapons during the flight.

Surveillance camera videos posted on Russian social networks showed the fighter in a nearly vertical dive and then exploding. Other videos showed the building engulfed by flames and firefighters deployed to extinguish the blaze.

Irkutsk, a major industrial center of more than 600,000 in eastern Siberia, is home to an aircraft factory producing Su-30s, a supersonic twin-engine, two-seat fighter that has been a key component of the Russian air force. China, India and many other countries also use the planes.

Sunday’s crash was the 11th reported noncombat crash of a Russian warplane since Moscow sent its troops into Ukraine on Feb. 24. Military experts have noted that as the number of Russian military flights increased sharply during the fighting, so did the number of crashes.