LAGOS, Nigeria (AP) — A commercial airliner crashed into a densely populated neighborhood in Nigeria’s largest city, 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.

SLIDESHOW: Aftermath of the tragic crash near Lagos

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.

While local residents helped carry fire hoses to the crash site, the major challenges of life in oil-rich Nigeria quickly became apparent as there wasn’t any water to put out the flames more than three hours later. Some young men carried plastic buckets of water to the fire, trying to douse small portions. Fire trucks, from the very few that are stationed in Lagos state with a population of 17.5 million, couldn’t carry enough water. Officials commandeered water trucks from nearby construction sites, but they became stuck on the narrow, crowded roads, unable to reach the crash site.

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.

Nigeria, home to more than 160 million people, suffers from endemic government corruption and mismanagement. The nation also has a history of major aviation disasters, though in recent years there hasn’t been a crash. In August 2010, the U.S. announced it had given Nigeria the Federal Aviation Administration’s Category 1 status, its top safety rating that allows the West African nation’s domestic carriers to fly directly to the U.S.

But many travelers remain leery of some airlines. On Saturday night, a Nigerian Boeing 727 cargo airliner crashed in Accra, the capital of Ghana, slamming into a bus and killing 10 people. The plane belonged to Lagos-based Allied Air Cargo.

Officials with Lagos-based Dana Air did not respond to calls for comment Sunday night. The airline has five aircraft in its fleet and runs both regional and domestic flights. Local media reported a similar Dana flight in May made an emergency landing at the Lagos airport after having a hydraulic problem.

Nigeria has tried to redeem its aviation image in recent years, saying it now has full radar coverage of the entire country. However, in a nation where the state-run electricity company is in tatters, the power grid and diesel generators sometimes both fail at airports, making radar screens go blank.

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.

The crash also comes as Nigeria, which became a democracy in 1999 after years of military rule, faces increasing sectarian bloodshed across its largely Muslim north from a radical Islamist sect known as Boko Haram. Earlier Sunday, a suicide car bomber killed at least 15 people and wounded dozens of others.

As night began to fall Sunday, more and more worried relatives of passengers arrived in the neighborhood, pushing their way down the crowded, narrow streets to make it to the crash site. One man stopped to ask about the crash, whether any passengers walked away alive.

His eyes grew wide when he heard no one escaped alive, his hand rising to his mouth. His brother was onboard.

“Oh God, we lost him,” the man whispered, before slowly walking away.

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Associated Press writers Yinka Ibukun and Lekan Oyekanmi in Lagos, Nigeria; Bashir Adigun in Abuja, Nigeria, and Carley Petesch in Johannesburg contributed to this report.

Copyright 2012 The Associated Press.