LAGOS, Nigeria — A commercial airliner crashed into a densely populated neighborhood in Nigeria’s largest city on Sunday, killing all 153 people on board and others on the ground in the worst air disaster in nearly two decades for the troubled nation.

The cause of the Dana Air crash remained unknown Sunday night, as firefighters and police struggled to put out the flames around the wreckage of the Boeing MD83 aircraft. Authorities could not control the crowd of thousands gathered around to see the crash site, with some crawling over the plane’s broken wings and standing on a still-smoldering landing gear.

Harold Demuren, the director-general of Nigeria’s Civil Aviation Authority, said all on board the flight were killed in the crash. Lagos state government said in a statement that 153 people were on the flight traveling from Nigeria’s central capital of Abuja to Lagos in the nation’s southwest.

The flight’s pilots radioed to the Lagos control tower just before the crash, saying the plane had engine trouble, a military official said. The official spoke on condition of anonymity as he was not authorized to speak to journalists.

Rescue officials feared many others were killed or injured on the ground, but no casualty figures were immediately available. Firefighters and local residents were seen carrying the corpse of a man from one building, its walls still crumbling and flames shooting from its roof more than an hour after the crash.

President Goodluck Jonathan later declared three days of national mourning in Africa’s most populous nation.

Jonathan “prays that God Almighty will grant the families of the victims of the plane crash the courage and fortitude to bear their irreparable loss,” a statement from his office read.

The aircraft appeared to have landed on its belly into the dense neighborhood that sits along the typical approach path taken by aircraft heading into Lagos’ Murtala Muhammed International Airport. The plane tore through roofs, sheared a mango tree and rammed into a woodworking studio, a printing press and at least two large apartment buildings in the neighborhood before stopping.

A white, noxious cloud rose from the crash site that burned onlookers’ eyes, as pieces of the plane lay scattered around the muddy ground.

The dead included at least four Chinese citizens, the official Chinese news agency Xinhua reported late Sunday, citing Chinese diplomats in Nigeria. Officials at the Chinese embassy in Nigeria could not be reached for comment by the AP.

Sunday’s crash appeared to be the worst since September 1992, when a military transport plane crashed into a swamp shortly after takeoff from Lagos. All 163 army soldiers, relatives and crew members on board were killed.