The Russian navy grounded its Pacific fleet aircraft Saturday after a reconnaissance plane crashed off Sakhalin Island, leaving 11 people missing.

The wreckage of the Tu-142M3 Bear-F was discovered Saturday in 144 feet of water a few hours after the four-engine, turboprop aircraft went down during a training mission Friday night.

"A special commission is investigating the causes of the crash of the

plane, which had 11 people on board, a fleet spokesman said. "Flights have been suspended until the investigation is complete. The search for the missing crew is still under way."

A preliminary investigation blamed the crash on a mechanical failure, RIA Novosti reported.

The next step will be recovering the plane's black box, which might require the use of an unmanned vehicle, the Russian news agency said.