Investigators believe that an explosion aboard a plane in Somalia was likely caused by a small bomb that was placed inside of a laptop, sources familiar with the probe said.
A small team of FBI agents has arrived in Somalia to help authorities in the East African nation investigate the cause of the explosion this week at 11,000 feet.
The A-321 jetliner made an emergency landing and returned to the airport, but two passengers were hurt. It's believed one person may have been sucked out of the plane through a relatively small hole left by the explosion -- possibly the bomber.
It is still unclear exactly who is responsible for planning the explosion, but authorities are looking into whether the al Qaeda-linked terrorist group al-Shabab, based in Somalia, may be behind it, and they're not ready to rule out ISIS, sources said.
Many of the passengers on the flight were originally scheduled to be on a Turkish Airlines flight but the flight was canceled "due to operational reasons" and bad weather, according to Turkish Airlines spokesman Yahya Ustun.
An FBI spokesman declined to comment for this article, referring questions to Somali authorities.
ABC News' Erin Dooley contributed to this report.