MOGADISHU, Somalia — An explosion that blew a hole in a jetliner shortly after takeoff and left one man missing was believed to have been caused by a bomb, the pilot said Wednesday, describing how the crew calmed frightened passengers as smoke enveloped the cabin before he brought the plane back to Mogadishu’s airport for an emergency landing.

Residents of Balad, a town about 18 miles north of Mogadishu, found the body of a man who might have been blown out of the Airbus 321 in Tuesday’s blast, said police officer Mohamed Hassan.

Abdiwahid Omar, the director of Somalia’s civil aviation authority, told state-run Radio Mogadishu that authorities were not sure if the body was that of the missing passenger.

Government officials said no evidence had been found of a criminal act.

Mohammed Ibrahim Yassin, CEO of Daallo Airlines, did not rule out that a bomb was planted on the aircraft.

‘‘At this stage, everything is possible. We cannot rule out anything at this stage,’’ Yassin said.

No group claimed responsibility for the blast. Somalia faces an insurgency from the Islamic extremist group al-Shabab, which has carried out many deadly attacks across the nation.

Pilot Vlatko Vodopivec said he and others were told the explosion was caused by a bomb.

‘‘It was my first bomb; I hope it will be the last,’’ Vodopivec said by phone from Mogadishu. He said the blast happened when the plane was at around 11,000 feet and climbing to its cruising altitude of 30,000 feet.

‘‘It would have been much worse if we were higher,’’ he said.

Had the blast occurred at a higher altitude, it could have led to explosive decompression on the plane, which might have caused more severe structural damage and would have forced a more rapid descent because of limited supplies of oxygen to the passengers.

Daallo Airlines said all passengers except one got off the plane safely. It previously said the plane, which was headed to Djibouti in the Horn of Africa, carried 74 passengers.

Yassin acknowledged that signs pointed to the possibility that a passenger was sucked from the plane at the time of the blast.

‘‘Maybe one person fell out of the hole. But nothing is sure,’’ he said from Dubai, United Arab Emirates, where the airline has its commercial offices.

Cellphone video taken during the flight showed passengers, some wearing oxygen masks, sitting toward the back of the jet, with empty seats in the front of the cabin near the hole in the fuselage. A loud sound of rushing air could be heard on the video, which was shot by Awale Kullane, Somalia’s deputy ambassador to the United Nations.

The passengers bunched in the back appeared calm. A child wearing an oxygen mask sat quietly, partially covered by a blanket. Near the hole, oxygen masks dangled and swayed from overhead compartments.

‘‘When we heard a loud bang, the co-pilot went back to the cabin to inspect the damage, and I took over the commands as the procedure demands,’’ the Serbian pilot said, adding that the engines and hydraulics functioned normally so he had no problem flying the aircraft back to Mogadishu.

‘‘Smoke came into the cockpit, but it was mostly concentrated in the back of the aircraft,’’ he said. ‘‘The stewardesses did a great job calming down the passengers and following the emergency procedure.

‘‘I think for the first few seconds and minutes . . . . I was terrified and most people were terrified,’’ he said.