Islamic State Claims It Downed Russian Airliner — But Cause Remains Unclear

Investigators are still searching for answers after a Russian jetliner crashed in Egypt on Saturday, killing all 224 passengers and crew members aboard. An Islamic State (IS) affiliate has claimed responsibility for downing the jet, but experts working at the crash site say they haven't found conclusive evidence to confirm the cause.

"It's too early to make any conclusions. The destruction [of the plane] happened in the air and the fragments scattered over a large area (around 20 square kilometers)," said Victor Sorochenko, the executive director of Russia's Interstate Aviation Commission, according to RT.

Related: Russian Airliner Crashes in Egypt's Sinai Peninsula With 224 People Aboard

Video footage of the crash site showed the ruins of the Russian Metrojet plane, which was carrying vacationers from the Red Sea resort of Sharm el-Sheikh to St. Petersburg before it went down. An Egyptian ground service official who carried out a pre-flight inspection said Sunday that the Airbus A321 appeared to be in good condition.

"We are all shocked. It was a good plane. Everything checked out in 35 minutes," the official told The Associated Press. The Russian A321 aircraft, which crashed over Egypt's Sinai Peninsula on Saturday, fell apart in the air.

On Saturday, IS affiliate Wilayat Sinai claimed responsibility for the crash via social media. "The fighters of the Islamic State were able to down a Russian plane over Sinai province that was carrying over 220 Russian crusaders. They were all killed, thanks be to God," the group's statement read.

Russia's transport minister has written off the claims, saying they "can't be considered accurate."

Wilayat Sinai also released a video on Sunday titled "From Sinai to Jerusalem," which calls for attacks on Israel and includes footage of recent attacks in Israeli territory, but doesn't make mention of the crash.

Wilayat Sinai was created in November 2014, when Egypt's most active militant group Ansar Bayit al-Maqdis announced it had pledged allegiance to IS leader Abu Bakr al-Baghdadi. The group has since carried out a number of attacks against security forces in the Sinai, including a ground assault against as many as 21 Egyptian military and police positions near the town of Sheikh Zuweid in July. In 2014, the group took credit for the murder of William Henderson, an American who was killed while working in Egypt.

Related: Sinai Militants Bring Down a Helicopter, But With Whose Missile?

The group's statement did not indicate how the militants allegedly downed the Russian aircraft. Radio Free Europe reported that some IS supporters on Twitter claimed that IS's Sinai affiliate possessed Igla surface-to-air missiles, and that Israeli officials have also claimed that Wilayat Sinai has released footage showing its militants apparently firing an Igla (SA-18) weapon. In January 2014, the militants claimed to have shot down an Egyptian military helicopter.

Since the crash, Russia has grounded its Airbus A321 jets and several UAE Carriers said on Sunday that they were re-routing flights to avoid flying over the region. Security precautions are being taken by Russia's the Kogalymavia airline, Emirates airline, Air Arabia, and Flydubai airlines until the details behind the crash become more clear.

Day of mourning in Russia. People lay toys, flowers for — RT (@RT_com)November 1, 2015

Egyptian and Russian investigators will begin examining the contents of two "black box" flight recorders recovered from the airliner, which crashed into a mountainous area of central Sinai around daybreak shortly after losing radar contact near cruising altitude.

Egyptian Prime Minister Sherif Ismail told a news conference late on Saturday that there did not appear to be any unusual activity behind the crash, but added that investigations are still underway.

Follow Atoosa Moinzadeh on Twitter: @amoinzadeh

Reuters contributed to this report.