Updated from 8:33 p.m. EDT
Two Russian planes crashed almost simultaneously Tuesday, with more than 90 people feared dead, according to wire service reports.
President Vladimir Putin ordered the country's security service to investigate.
reported that witnesses saw an explosion on board one of the planes before it crashed near Tula, which is 90 miles south of Moscow. There was no word on survivors.
The Tu-134 airliner with 34 passengers and eight crew members flying from Moscow to Volgograd crashed after contact with it was lost around 3 p.m. EDT,
Three minutes later, air traffic controllers lost contact with another passenger plane -- a Tu-154 with 44 passengers and eight crew on board -- flying from Moscow to Sochi, near the Black Sea.
reported late Tuesday that that plane also had crashed.
The crashes took place days before Sunday's election in the contentious region of Chechnya, where Russia has been resisting a separatist movement for five years.