The wreckage of the Russian Tu-154 airliner which went missing Tuesday night and remains of some passengers have been found in the Rostov region, an Emergency Situations Ministry spokesman said Wednesday.

Wreckage of second Russian plane found

An emergency official said the plane apparently had broken up in the air.

The Interfax news agency said earlier that an alarm went off aboard the Tu-154 airliner just before it went missing in southern Russia, indicating the plane underwent an attack or hijacking.

The signal came at 11:04 p.m. (1904 GMT) Tuesday from the Tu-154 airliner that disappeared in southern Russia's Rostov region, the report quoted a Russian official as saying.

The plane, with 44 people on board, went missing from radar screens en route Moscow to the Black Sea resort city of Sochi.

The Tu-1154 airliner lost contacts at 22:59 Moscow time (1859 GMT) when it was expected to be 140 km from the city, said the report.

Almost the same time, another passenger jet Tu-134, with 44 people on board including eight crew members, crashed in the Tula region south of Moscow, killing all the people on board, said the Russian emergency ministry.

The rescuers have found the plane's tail and were searching for other pieces, flight recorders, as well as possible survivors.

Report said the plane took off Moscow's Domodedovo airport and headed for Volgograd at 22:32 Moscow time (1832 GMT). Communication with the aircraft was lost at 22:59 Moscow time (1859 GMT).

Witnesses said they saw an explosion on board the plane just before it crashed.

Russian President Vladimir Putin has ordered the Federal Service of Security to investigate the two incidents immediately, Putin's press secretary Alexei Gromov said.

Meanwhile, security has been tightened at all the country's airports after the crashes, as the Russian authorities have not ruled out terrorist attacks against the aircraft.

A presidential election was scheduled to be held in Chechnya, a breakaway republic of Russia, on Sunday, and separatist rebels there have been blamed for a series of terror strikes that have claimed hundreds of lives.

All 44 aboard crashed Russian airliner dead

All 44 passengers and crew aboard a Russian Tu-134 airliner which crashed Tuesday were killed, the Interfax news agency reported early Wednesday.

Rescuers found the airplane's main section some two km off Buchalki village in the Tula region, about 180 km south of Moscow, the Interfax quoted an Emergency Ministry official as saying.

The Tupolev aircraft was en route from Moscow to Russia's southern city of Volgograd when it disappeared off radar screens at 2300 (1900 GMT) Tuesday.

Backgrounder: Basic information about Tu-154 and Tu-134

A Russian Tu-134 airliner crashed Tuesday with all 44 passengers and crew aboard killed, the Russian emergency ministry said early Wednesday.

Also on Tuesday, a Tu-154 airliner went missing in southern Russia's Rostov region.

The Interfax news agency quoted a Russian official as reporting Wednesday that an alarm aboard went off just before it disappeared, which indicated an attack or hijacking.

The following are the basic information about Tu-154 and Tu-134planes.

The Tu-154 first flew on Oct. 4, 1968. Regular commercial service began in February 1972.

It is 47.2 meters long and 11.2 meters high. The maximum speed is more than 900 kilometers per hour.

The plane, with three or four flight crew, has more than 150 seats.

About 900 Tu-154s of all models have been produced till now.

The production of Tu-134 planes started in 1964. Aeroflot launched full commercial service in September 1967.

The Tu-134 can seat 76 people in a single class. The revised Tu-134B1, which has a revised interior, can seat up to 90 passengers without a galley, or kitchen. And the Tu-134B3 can seat 96 with a full kitchen.

It is 33.8 meters long and 8.9 meters high. The maxium speed is899 kilometers per hour.

The Tu-134, with three flight crew, can seat 72 to 96 passengers.

About 365 TU-134s were in service in late 1998.

Backgrounder: Major air crashes since 2003

Two Russian passenger airliners with a total of more than 80 people on board crashed almost simultaneously late Tuesday and no survivors were reported so far.

A Tu-134 jet carrying 34 passengers and eight crew members crashed near the village of Buchalki in the Tula region south of Moscow.

The wreckage of the second crashed plane, a Tu-154 jetliner, which flew from Moscow to the Black Sea resort of Sochi with 44 passengers and eight crew members aboard, has been found.

The following is a chronology of major air crashes since 2003.

Jan. 8, 2003 -- A total of 75 passengers and crew were killed when a Turkish RJ-100 jetliner, on a flight from Istanbul, crashed in heavy fog at Diyarbakir airport in southeastern Turkey. Five people survived.

Jan. 9, 2003 -- A Peruvian airliner crashed in northern Peru, killing 46 people aboard.

Feb. 1, 2003 -- Seven astronauts were killed as US space shuttle Columbia broke apart on its way back to the ground.

Feb. 19, 2003 -- An Iranian military plane crashed near Kerman in southeastern Iran. Iran said all 276 soldiers and crew aboard were killed.

March 6, 2003 -- An Algerian flag carrier Boeing 737-200 crashed shortly after take-off from Tamanrasset airport, killing at least 102 passengers and crew.

May 26, 2003 -- A Ukrainian YK-42 passenger plane heading to Spain crashed near the Trabzon Airport in northeastern Turkey, killing 74, including 62 Spanish soldiers returning from their peacekeeping mission in Afghanistan.

July 8, 2003 -- A Sudanese Boeing 737 crashed shortly after taking off from Port Sudan airport, killing 104 passengers and 11 crew members. A two-year-old passenger was the only survivor.

Dec. 25, 2003 -- A Boeing 727 owned by Union des Transports Africains crashed en route Beirut over the coastal capital of Cotonou, Benin, with 151 passengers and 10 crew members on board. Only 21 people survived.

Jan. 3, 2004 -- An Egyptian Boeing 737 crashed into the Red Seashortly after taking off from the resort of Sharm el-Sheikh, killing all 135 passengers and 13 crew members aboard.

Feb. 10, 2004 -- An Iranian Kish Airlines plane crashed in the United Arab Emirates. Forty-three of the 46 people on board died.

Source: Xinhua