Investigators searched the still-smoldering wreckage of a jetliner that slammed into the Nigerian bush, seeking flight-data recorders and other clues Monday to the cause of the crash that killed all 117 people aboard.

After much confusion about whether anyone had survived in the immediate aftermath of the Saturday evening crash, Nigerian officials confirmed Monday that all passengers and crew were dead.

"We can say all the people on board the aircraft perished," Information Minister Frank Nweke Jr. (search) told state radio.

Fidelis Onyenyiri, chief of the National Civil Aviation Authority (search), said the crash appeared to be an accident.

"The weather was not too bad, but there was lightning, and an airplane struck by lightning could lose total control," Onyenyiri told reporters on Sunday. "So there is a likelihood of a natural cause."

The impact appeared to cause the plane's virtual disintegration. Small bits of fuselage, human flesh and clothing were strewn in nearby trees. A hand and leg lay on the ground. No identifiable bodies could be seen but the smell of death hung in the air.

Acrid smoke still curled from the eight-yard-deep pit as investigators picked through wreckage, looking for flight-data recorders — the so-called black boxes, which are actually often blaze orange for easier identification.

"We are here to secure the site to enable the investigators to do their work. They're trying to find the black boxes so we can determine the cause of the crash," said one member of Nigeria's security forces at the scene. He asked not to be identified because he wasn't authorized to speak to reporters.

Military helicopters first spotted the smoldering wreckage of the Nigerian-run Bellview jet on Sunday morning, and search teams that visited the site afterward found no survivors, said Onyenyiri.

The plane lost contact with the Lagos control tower five minutes after taking off from Murtala Muhammed International Airport in Lagos at 8:45 p.m. on Saturday, said Jide Ibinola, a spokesman for the Federal Airport Authority of Nigeria. State radio said pilots issued a distress call before the plane disappeared from radar.

The plane was headed to the capital, Abuja, on what was supposed to have been a 50-minute flight, a route popular among Nigerians and expatriates.

The nationalities of those aboard were not immediately known, but most were believed to be Nigerians. State Department spokesman Edgar Vasquez said one American aboard the flight had been killed, but he did not identify the person.

Airline officials said 117 people were on board — 111 passengers and six crew members.

Nigeria announced a three-day, nationwide mourning period for victims of the Bellview Airlines Boeing 737-200, which plowed a deep crater into the ground near Lissa shortly after take off from Lagos airport, 30 miles to the south.

Bellview, one of about a dozen local airlines plying Nigeria's skies, is a privately owned Nigerian company that operates a fleet of mostly Boeing 737s on internal routes and throughout West Africa, as well as London. Bellview first began flying about 10 years ago, and this was the company's first crash.

Many consider Bellview to be among the most reliable of the airlines shuttling between Nigeria's often-chaotic regional airports, which can resemble bus depots where crowds battle for seats on planes.

In May 2002, an EAS Airlines jet plowed into a heavily populated neighborhood after takeoff at the airport outside the northern city of Kano, killing 154 people in the plane and on the ground.