Buchalki, Russia ? A Russian airliner crashed and another apparently broke up in the air almost simultaneously after they took off Tuesday night from the same Moscow airport, officials said, raising fears of terrorism and leaving little hope that any of at least 89 people on board could have survived.

Authorities said rescuers found wreckage from a Tu-154 jet, which was carrying at least 46 people, about nine hours after it issued a distress signal indicating an attack and disappeared from radar screens over the Rostov region some 600 miles south of Moscow.

About the same time that plane disappeared, a Tu-134 airliner carrying 43 people crashed in the Tula region, about 125 miles south of Moscow, officials said. The Emergency Situations Ministry later said that everybody on board the Tu-134 was killed.

The planes had left Moscow’s Domodedovo airport within 40 minutes of each other Tuesday night and disappeared from radar screens about 11 p.m, officials said.

President Vladimir Putin ordered an investigation by the nation’s main intelligence agency, the Federal Security Service, and security was tightened at airports across the country.

Authorities have expressed concern that separatists in war-ravaged Chechnya could carry out attacks linked to Sunday’s election to replace the region’s pro-Moscow president, who was killed by a bombing in May. Rebels have been blamed for a series of terror strikes that have claimed hundreds of lives in Russia in recent years.

Witnesses reported seeing an explosion before the first plane crashed about 125 miles south of Moscow, and suspicions of terrorist involvement were compounded by the reports that the Tu-154 airliner that went missing in southern Russia’s Rostov region issued a signal indicating the plane was being seized.

Citing an unidentified source in Russia’s government, Interfax said the signal came at 11:04 p.m., shortly before the plane disappeared from radar. Emergency and Interior Ministry sources in southern Russia, speaking on condition of anonymity, also told The Associated Press a distress signal had been activated.

The Interfax news agency said emergency workers spotted a fire in the Rostov region, some 600 miles south of Moscow, where the Tu-154 went missing. But rainy weather hampered the search efforts and it took hours before any wreckage was found.

In Washington, a U.S. official, speaking on condition of anonymity Tuesday evening, said it was the understanding of American officials that the two Russian planes disappeared within four minutes of each other, which “in and of itself is suspicious.”