Mysterious double crash puts Russia on edge; officials say no evidence yet of terrorism

BUCHALKI, Russia — Russian investigators labored Wednesday to determine whether terrorism caused the near-simultaneous crashes of two jetliners, killing all 89 people aboard and spreading anxieties about a possible bloody escalation of the Chechen conflict.

Officials stressed that no evidence of a terrorist attack had yet been found among charred wreckage and said they were looking at other possibilities like bad fuel, equipment malfunction and human error. The planes' data recorders were recovered, but experts were only just starting to retrieve information from them.

The planes plunged just days before a Kremlin-called presidential election in Chechnya, whose rebels have staged suicide bombings and other attacks across Russia in recent years, including the 2002 seizure of hundreds of hostages at a Moscow theater.

Russian authorities had expressed concern the separatists might stage new attacks before the Sunday vote, but there was no rush to tie the crashes to Chechnya — a determination that would underline the government's failure to quell the decade-old insurgency.

"Several versions are being examined, including a terrorist attack, and other possibilities — the human and technical factor," Russia's top prosecutor, Vladimir Ustinov, told President Vladimir Putin during a televised meeting about the Tuesday night crashes.

Putin, who expressed sympathy for the families of the dead, didn't publicly address the terror question. After designating Thursday as a national day of mourning, he ordered that the Federal Security Service investigate the crashes and said he wanted "unbiased and reliable information" from the probe. The service is a successor agency to the KGB.

While officials spoke cautiously on the terrorism issue, Russian police said security was being tightened at airports and other transport hubs and public places.

In Washington, U.S. officials said they had no information on the disaster, but said American agencies were ready to provide help if asked.

"Our understanding is, there is no cause that has been ruled in or no cause that has been ruled out," said State Department deputy spokesman Adam Ereli.

Outside experts expressed skepticism that anything but violence could be behind two planes crashing at almost the same time hundreds of miles apart.

"That's pretty far out there on the chance bar," said Bob Francis, former vice chairman of the U.S. National Transportation Safety Board.