The number of plane crash victims identified by grief-stricken Russian families rose to 33 on Wednesday as rescue teams in Egypt combed the Sinai desert for more remains and parts of the plane's fuselage.

The Metrojet Airbus A321-200 carrying Russian vacationers from Sharm el-Sheikh in Egypt back to Russia's second-largest city of St. Petersburg crashed over the Sinai Peninsula early Saturday, killing all 224 people on board.

Only one body has been released to a Russian family for burial so far. Relatives have identified 33 bodies and the paperwork is close to ready on 22 of those, meaning the families should get the bodies shortly, Igor Albin, deputy governor of St. Petersburg, said in a televised conference call.

Russians were still seen sobbing in grief Wednesday at the unruly pile of flowers, photos and stuffed animals at the entrance to St. Petersburg's Pulkovo Airport.

In the Sinai, Russian and Egyptian rescue workers were still scouring the desert after expanding their search area to 40 square kilometers (15 square miles). The Russian state television channel Rossiya-24 reported the plane's tail was found 5 kilometers (3 miles) away from the rest of the wreckage.

Russian officials say the plane broke up in the air 23 minutes after takeoff after reaching an altitude of 31,000 feet. But they have refrained from announcing the cause of the crash, citing the ongoing investigation.

Metrojet, the plane's owner, and Russian authorities offered conflicting theories of what happened. Metrojet officials have insisted the crash was due to an "external impact," not a technical malfunction or pilot error. Russian officials have said it's too early to jump to that conclusion.

Two U.S. officials told The Associated Press on Tuesday that U.S. satellite imagery detected heat around the jet just before it went down.

The infrared activity could mean many things, however, including a bomb blast or an engine on the plane exploding due to a malfunction. One of the officials who spoke condition of anonymity because they weren't authorized to discuss the information publicly said a missile striking the Metrojet was ruled out, because neither a missile launch nor an engine burn had been detected.

Some aviation experts had earlier suggested a bomb was the most likely cause of Saturday's crash, while some others pointed to a 2001 incident in which the Metrojet plane damaged its tail during a rough landing.