A Russian plane crashed in Egypt's Sinai Peninsula in the morning of October 31, killing all 224 people on board.

A senior Russian aviation official said the plane broke in midair, after visiting the crash site on Sunday. It is not usual for modern planes to fall apart during flight, unless being bombed or hit by a missile, reported The Chicago Tribune.

An official with the Interstate Aviation Committee said it is still early to tell the cause of the accident. A pilot on the flight was said to complain to his wife about the plane's condition before takeoff, reported a Russian TV station. Russian and Egyptian officials denied the claims of the Islamic State militant group that it downed the Russian plane on Sinai Peninsula.

The plane's debris was spread out over seven square miles in Central Sinai, where militants waged a violent anti-government insurgency.

Located in northeastern Egypt, the triangular 61,000-square kilometer Sinai Peninsula has been in turmoil amidst militant attacks on security forces in the area for the past 2.5 years. The peninsula is nestled between the Red Sea in its south and the Mediterranean Sea on its north, and divided into South Sinai and North Sinai. The south has eight towns while the north has six, said the Middle East Monitor.

The crash happened weeks after Russian warplanes started to target the rebel positions in Syria, the Islamic Sinai's affiliate quickly had the chance to declare that the plane crash was their retaliation.

It is still unclear why the Russian plane rapidly fell to the Sinai Peninsula from about 31,000 feet after takeoff from Sharm al-Sheikh resort town, Egypt, said Russian Transport Minister Maxim Sokolov on Sunday.

The minister had a team of experts with him when he arrived in Egypt, reportedly to help in the investigation, but they have gathered only "little information."

The two flight recorders from the ill-fated plane are already being analyzed by the Civil Aviation Ministry at the Cairo ministry headquarters.