By: Regina Wright ~Staff Writer~

244 passengers on Russian-bound Metrojet Flight 9268 were killed after the plane crashed in Egypt’s Sinai Peninsula on Oct. 31. As the plane ascended on autopilot 23 minutes into the flight, a noise was heard from the cockpit voice recording in the final seconds before the plane crashed.

U.S. and British intelligence believe the crash was caused by a bomb placed by the Islamic State of Iraq and Syria (ISIS). U.S. and British intelligence intercepted communications from known ISIS affiliates in Sinai and ISIS operatives in Syria after the crash.

An investigation of the type of bomb and detonator is still underway. Egyptian officials have yet to confirm it was a bombing that caused the crash. Ayman al-Muqaddamhead, of the Egyptian-led committee looking into the crash, said it was premature to declare any official explanations for the incident, but they were investigating the noise heard in the cockpit voice recording before the plane went down.

The investigation into the voice recording includes Russia, Egypt, France, Germany and Ireland. Russian officials asked the F.B.I. to help them with the investigation. Debris from the plane was spread across an area of more than 13 miles, pointing to an inflight breakup.

On Friday, Russian officials grounded all flights to Egypt to investigate the traces of the explosives in samples of soil, luggage and portions of the plane recovered from the crash site. All Russian tourists were called to return home. They were only allowed to bring carry-on luggage with them on returning flights, while another plane transported the rest of their cargo. As a precautionary step, Homeland Security will increase security on international flights into the U.S.