MOSCOW -- One passenger plane crashed and a second apparently broke up in flight almost simultaneously after they took off from the same airport south of Moscow late yesterday in what authorities feared may be Russia's worst militant attack since the seizure of a Moscow theater in October 2002.
The Russian news agency Interfax reported that a hijacking signal was activated on the second plane before it disappeared from radar screens.
One plane, with 43 aboard, took off from Domodedova Airport and crashed near the village of Buchalki in the Tula region, 125 miles south of Moscow, at 10:56 p.m. local time (2:56 p.m. EDT).
Another plane took off from the same airport 40 minutes later, then vanished from radar screens with 46 people aboard about 11 p.m. local time (3 p.m. EDT) near the city of Rostov-on-Don in southern Russia, about 600 miles south of the capital.
Officials reported a large fire near Rostov, which could have been the second plane. A Russian emergency official said pieces of wreckage from the plane had been found.
There were no reports of survivors in either incident.
The news agency ITAR-Tass reported that authorities were not ruling out sabotage or seizure of the planes by militants. Russia is entering its fifth year of war with Chechen separatists, a struggle that the Kremlin calls part of the international struggle against Islamic extremism.
The Itar-Tass news agency reported that witnesses saw a flash before the first plane, a Tu-134 operated by Volgograd-based airline Volga-Aviaexpress, crashed.
Because the wreckage was spread over such a wide area, local authorities said the passenger jet evidently plunged to the ground after exploding. The plane was headed to the southern city of Volgograd, on the Volga River.
The second plane, a Tu-154 operated by Siberia Airlines, was headed to the Black Sea resort of Sochi, where Russian President Vladimir V. Putin is on vacation.
The regional Emergency Situations Ministry chief Viktor Shkareda told the Associated Press that the plane apparently broke up in the air and that wreckage was spread over an area of some 25-30 miles. Body parts have also been found with fragments of the plane, Interfax quoted federal Emergency Situations Ministry as saying. It said the parts were found near Gluboky, a village north of Rostov-on-Don.
Though emergency officials in Moscow put the number of passengers and crew at 46, Shkareda said there were 52 people aboard the plane.
Putin said he would take charge of the investigation, Russian news agencies reported. He ordered the Federal Security Service, the nation's top security agency, to determine the cause or causes.
Told about the two crashes, Russia's U.N. Ambassador Andrey Denisov said, "Now we have to see if there's terrorism," according to wire reports.
A senior U.S. State Department official said in Washington that the White House was "concerned" about the incidents.
"We're following developments closely and trying to determine the facts," the official said.
Presidential elections in Chechnya are days away. The vote was called to replace President Akhmad Kadyrov, a pro-Moscow Chechen clan leader who was assassinated May 9 in an explosion at a stadium in the Chechen capital, Grozny.
Voting is scheduled for Sunday in Chechnya, but the outcome seems certain. The pro-Moscow candidate, Alu Alkhanov, has received intensive, positive coverage in the state-controlled media.
Suspicion in yesterday's incidents immediately fell on Chechen rebel leader Shamil Basayev, who claimed responsibility for the assassination of Kadyrov and several other attacks, including the one on the Moscow theater.
The 2 1/2 -day standoff in the Dubrovka Theater ended in the deaths of at least 129 hostages, who evidently succumbed to an anesthetic gas used by Russian authorities to knock out the guerrillas. Many of the more than 40 hostage-takers were killed by Russian special forces.
In an extensive rebel assault in Grozny Saturday, 300 armed men fired on police stations and polling places. At least 20 law enforcement officers were killed in the fighting, which raged for three hours.
Four people were injured last night when a bomb exploded at a Moscow bus stop. It was not clear whether a bus was the intended target or whether the blast was meant to damage nearby kiosks in what authorities described as a local business dispute.
Bombing attacks in Russia since December 2002:
May 9: A bomb rips through a stadium in the Chechen capital, Grozny, during a Victory Day ceremony, killing provincial President Akhmad Kadyrov, the Kremlin's point man for efforts to control separatist violence in the war-racked region. As many as 24 are killed. A Chechen warlord claims responsibility.
Feb. 6: An explosion on a subway car in Moscow during rush hour kills 41. Authorities suspect a militant attack.
Dec. 9: A female suicide bomber blows herself up outside Moscow's National Hotel, across from the Kremlin and Red Square, killing five bystanders.