Two passenger jets that took off from a Moscow airport crashed within minutes of each other in different parts of Russia late Tuesday night with a total of at least 88 people on board, authorities said. No survivors were reported.

The two planes left Moscow's Domodedovo Airport barely a half-hour apart, heading to separate destinations, and then disappeared from radar almost simultaneously about 11 p.m., authorities said. Rescue squads reached the scene of one crash in the Tula region, about 100 miles south of Moscow, early Wednesday morning and hours later found the fiery wreckage of the second plane near the southern city of Rostov-on-Don, about 600 miles south of Moscow.

Officials made no immediate statements about the possible causes of the twin crashes but the timing raised suspicions of a terrorist attack. Witnesses in Tula reported seeing an explosion before the plane there plunged out of the sky, while the other plane activated a signal reporting it had been hijacked, according to the Interfax news agency.

President Vladimir Putin, who is vacationing at the Black Sea resort of Sochi, where one of the planes was heading, was quickly informed of the developments and ordered the Federal Security Service, the domestic successor to the KGB, to investigate the incident, the Kremlin said. Security was quickly tightened at Russian airports.

"There's shock," Ilya Novokhatskiy, an official at Sibir airlines, said by telephone as he tried to gather information on the crash of its plane near Rostov-on-Don. "But we have to keep working." He said it was too early to say if terrorists were behind the crashes. "This just happened. We can't give versions of this. This will be for the official committee to assess."

The crashes took place five days before an election in the separatist region of Chechnya to choose a successor to Akhmad Kadyrov, the Kremlin-allied president of the Russian republic who was assassinated in May. The approaching vote has already been marked by renewed fighting in the Chechen capital of Grozny and elsewhere in the region.

Terrorists have targeted Russia repeatedly in the last two years, killing more than 500 people in Moscow and in the southern part of the country. Chechen guerrillas have claimed responsibility for many of the suicide bombings and other attacks, but they have never destroyed civilian passenger planes.

"There's still a chance this is an appalling airplane maintenance problem, but it seems more likely this is a terrorist act, given the prevailing conditions in the region," said Fiona Hill, a Russia scholar at the Brookings Institution in Washington. "The whole of the North Caucasus is in considerable disarray."

Russian government officials have sought repeatedly in recent years to link Chechen separatist guerrillas with international terrorist groups such as al Qaeda. But Hill said the possible airplane-based attack was not necessarily an indication of such cooperation.

"There's a situation where you have a demonstration effect -- what works in one place people adapt in another," she said. The fact that Putin is currently on vacation in Sochi would be "very symbolic, obviously," she added.

Aslan Maskhadov, the Chechen separatist leader, vowed in June to escalate attacks against Russians. "We're planning a change in our tactics," he said at the time. "From now on, we'll be launching big attacks."

Maskhadov seemed to foreshadow the use of airplanes in an e-mail sent to the Reuters news agency last month. "If Chechens possessed warplanes or rockets, then airstrikes on Russian cities would also be legitimate," he wrote.

Flight 1303, a Tupolev Tu-134 operated by Volga-Aviaexpress airline, took off from Domodedovo about 10 p.m. heading for the southern city of Volgograd, known as Stalingrad from 1925 until 1961, according to Russian news reports. It disappeared at 10:56 p.m. with 34 passengers and eight crew members aboard, including the head of the airline. Authorities found the scattered remains of the plane around the village of Buchalki in the Tula region.

Flight 1047, a Tupolev Tu-154 operated by Sibir, left Moscow about 9:30 p.m. heading for Sochi, then vanished from radar at 11 p.m., according to the airline. Sibir reported on its Web site that 38 passengers and eight crew members were aboard. More than nine hours after the crash, rescue personnel found the flaming debris of the plane about 82 miles north of Rostov-on-Don.

Authorities had anticipated a terrorist attack leading up to the election Sunday, which the regional interior minister, Alu Alkhanov, is expected to win with Kremlin support. Putin made a rare trip to Chechnya last weekend to lay a wreath along with Alkhanov at the grave of Kadyrov, the slain Chechen president. The ceremony took place the morning after Chechen guerrillas launched coordinated attacks killing at least 30 people.

In an interview Tuesday before the plane crashes, Tatyana Lokshina, executive director of the Moscow Helsinki Group, a human rights organization, said recent fighting in Grozny might be "some kind of prelude to some bigger event that would take place" on or before the election.

Terrorist attacks in the last year have focused on what are known as soft targets, such as the Moscow subway and a rock concert. An explosion aboard a Moscow bus injuring four earlier Tuesday stoked fear. But security for domestic flights at Russian airport has often been criticized as lax.

"Chechen terrorists have said they would take the war to other parts of Russia, and it's not that hard to do if you look at . . . the security," said Sarah Mendelson, who specializes on Chechnya at the Center for Strategic International Studies in Washington. "They just haven't put in place the kind of measures to protect citizens."