Here’s what we know about the deadly Russian plane crash that killed all 224 people on board Saturday, Oct. 31. (Monica Akhtar/The Washington Post)

A Russian plane that crashed in Egypt over the weekend broke up in the air, a senior Russian aviation official said after visiting the crash site in the Sinai Peninsula on Sunday. All 224 people aboard were killed.

Modern planes don’t usually fall apart in flight, barring an explosion caused by a bomb or missile, but Viktor Sorochenko, an official with the Interstate Aviation Committee, said it is too early to tell what caused the crash, according to Russia’s Interfax news agency. A pilot on the flight complained to his wife about the condition of the ­Airbus 321-200 shortly before takeoff, a Russian TV station reported, and Russian and Egyptian officials denied claims by the Islamic State militant group that it had downed the plane.

Sorochenko said the debris field was spread out over seven square miles in a remote area of central Sinai, where Islamist militants have waged a violent anti-government insurgency.

The crash occurred just weeks after Russian warplanes began targeting rebel positions in Syria, and the Islamic State’s Sinai affiliate was quick to seize the opportunity to declare that it had shot down the plane in retaliation.

But Russian Transport Minister Maxim Sokolov said Sunday it was unclear why the plane suddenly and rapidly fell from roughly 31,000 feet shortly after takeoff Saturday from the Egyptian resort town of Sharm el-Sheikh.

Sokolov arrived in Egypt with a team of experts to help with the investigation but said “little information” had been gathered so far, the Reuters news agency reported.

Egyptian officials said the Civil Aviation Ministry was analyzing data from two recovered flight recorders now at the ministry headquarters in Cairo.

Four major international airlines and a regional carrier announced they would avoid flying over Sinai until investigators know what caused the crash of Flight 9268. The move by Lufthansa, Air France-KLM, Qatar Airways and the Dubai-based Emirates and FlyDubai airlines to divert flights from Sinai’s airspace underscored growing international concerns about the jihadists’ reach in the region.

The only U.S. airline that flies in the region, United, does “not see a need” to change its routes at this time, a spokesman said Sunday.

Germany’s Transportation Ministry urged the country’s airlines not to use the route the Russian plane was flying when it crashed, according to the Associated Press. Before the crash, the ministry had issued a warning to airlines about flying over the northern part of the peninsula, which is a militant stronghold.

The Islamic State’s local affiliate is believed by security experts to possess shoulder-fired anti-aircraft missiles that can hit low-flying aircraft in the area. But those weapons systems are not capable of hitting aircraft above 10,000 feet, analysts say.

In July 2014, Malaysian Airlines Flight 17 was shot down over eastern Ukraine by a warhead fired from a Russian-built Buk missile system, Dutch investigators said. That plane was flying at 33,000 feet after its departure from the airport in Amsterdam.

If militants in the Sinai were in fact responsible for the destruction of the Russian airliner Saturday, they could only have done so with the acquisition of a similar sophisticated weapons system — or through the placement of a bomb while the plane was still on the ground.

The Egyptian government said Sunday that 163 bodies had been recovered and transferred to three facilities outside Sinai. Some of the bodies would be repatriated to the Russian city of St. Petersburg, the flight’s destination, on Sunday, officials said. Hundreds of mourners bearing flowers and stuffed animals gathered at the city’s Pulkovo Airport.

The charter flight operated by the Russian carrier Metrojet disappeared from controllers’ radar 23 minutes after takeoff from Sharm el-Sheikh, a popular destination for Russian tourists, Russia’s Federal Air Transport Agency said. It was carrying 217 passengers and seven crew members, the Egyptian Civil Aviation Ministry said.

Among the passengers killed were four Ukrainian nationals and one Belarusan. The remaining passengers were Russian citizens, including 17 children, authorities said.

A terrorist attack on a plane full of Russian vacationers could dampen the enthusiasm of the Russian public for the Kremlin’s intervention in the Syrian civil war, although past terrorist attacks within Russia itself have generally led to increased support for the government. Russian officials announced Saturday that they had opened an investigation into potential safety violations by the airline. The Investigative Committee launched an immediate search of the airline’s offices in Moscow and its facilities at ­Domodedovo International Airport, southwest of the capital.

Over the past few decades, there have been a handful of cases of catastrophic failure while planes were aloft. In 2002, a Boeing 747 flown by China Airlines broke up in flight, killing 225, and metal fatigue was blamed. In 1985, a Japan Airlines plane, also a 747, crashed when a rear bulkhead blew out. Investigators pointed to a faulty repair job. In that accident, 520 were killed.

The Metrojet Airbus was built in 1997 and had more than 56,000 hours of flight time, according to the Airbus company.

The southern Sinai, far from militant activity near the Gaza Strip, has long been a favorite destination of Russians on package tours, with its warm waters, attractive beaches and low prices. Winter is the peak tourist season, but according to reports, several thousand Russian vacationers are there now. Russia has not announced any restrictions on flights to or from the Sinai.

Heba Habib in Cairo and Andrew Roth in Moscow contributed to this report.

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