Listen to the article (2 minutes) Explosions rocked two Russian air bases on Monday, while Ukrainian officials hinted they may strike deeper into Russian territory and Moscow fired a barrage of missiles at Ukrainian cities. Russian authorities said they were investigating the cause of the explosion at a military base near the town of Engels in Russia’s Saratov region. The regional governor, Roman Busargin, said law enforcement authorities were investigating the incident and that no civilians were injured.
