The Russian passenger plane that crashed in Egypt Saturday broke apart “in the air,” a senior official with Russia’s Interstate Aviation Committee said on Sunday.

“The disintegration happened in the air and the fragments are strewn over a large area,” committee chief Viktor Sorochenko was quoted as saying by RIA-Novosti news agency in Cairo, where he is part of an international panel of experts from Russia, Egypt, France and Ireland.

Sorochenko said it was “too early to draw conclusions” about what caused the crash on Saturday, which killed all 224 people travelling from Egypt’s resort Sharm el-Sheikh to Saint-Petersburg.

The Interstate Aviation Committee (MAK) is Russia’s top body for investigating air accidents. Sorochenko was appointed on Saturday to head a panel of crash experts to Egypt.

International investigators began to probe why the Airbus 321 went down. Russia’s emergency ministry officials said they need to comb through an area of about 16 square kilometres (six square miles) in the remote Sinai peninsula.

Investigators have recovered the plane’s “black box” flight recorder and the Egyptian government said Sunday its contents were being analyzed.