Somali authorities later discovered a body near Mogadishu they believe fell from the Daallo Airlines plane.
Late Tuesday night, a source with knowledge of the investigation told CNN that Somali authorities confirmed one passenger had been blown or ejected out of the hole created by the explosion. Somalia's National News Agency reported that one passenger died after falling from the plane.
Pictures from the ground showed a hole in one side of the airliner, just above its wing and slightly smaller than one of its doors.
Initial tests of the damage on Flight D3159 came back positive for explosive residue, a source with knowledge of the investigation told CNN.
A spokesman for Somali Prime Minister Omar Abdirashid Ali Sharmarke didn't immediately indicate a bomb had gone off mid-flight, echoing a Daallo Airlines worker in saying "the incident is under investigation."
"There is a lot of conflicting information," said the Prime Minister's spokesman, Abdisalam Aato.
Daallo CEO Mohammed Ibrahim Yassin told Forbes.com that it was too early to say what caused the explosion.
"Nothing is certain," he said. He acknowledged that some people believed there was a bomb. "The Civil Aviation (Authority) thinks differently."
An airport official estimated the Daallo plane was between 12,000 and 14,000 feet high when the blast occurred not long after it took off from Mogadishu International Airport.
The pilot then flew the Airbus A321-111, which had originated in Jeddah on Saudi Arabia's Red Sea coast, back to the Somali capital.
If this was a bomb, no group immediately took responsibility.
Al-Shabaab has been behind some of the worst violence in recent years in and around Somalia. Some of it targeted tourists, such as last month's deadly attack on a beachside restaurant-hotel complex in Mogadishu. Young people also have been targets, as shown in the massacre at Kenya's Garissa University College. And the general public hasn't escaped the group's violence, as evidenced in a 2013 assault on an upscale mall in Nairobi.
Yet this Islamist extremist group has recently gotten competition from ISIS, with a high-ranking Al-Shabaab member and spiritual leader pledging allegiance to the rival group last fall.
Flights in and out of Mogadishu International Airport were suspended briefly Tuesday because of the Daallo Airlines incident.
That airport is home to offices of the United Nations, African Union and many diplomatic missions, including those of the United States and European Union.
Daallo Airlines is based in the United Arab Emirates and has flights to Djibouti, Kenya, Saudi Arabia and Somalia.