The United States plans to work with the Nigerian army to help it combat the threat of the Islamist group Boko Haram which is spreading violence in the west African nation, officials said Tuesday.

But Washington has still not decided whether to put the group on a blacklist of terrorist organizations -- even as gunfire and explosions erupted in the Nigerian city of Maiduguri on Tuesday.

Nigerian rescuers have confirmed the first deaths on the ground following a devastating plane crash in the country's largest city of Lagos, raising the death toll to at least 157, an official said Tuesday.

Meanwhile, rains hampered efforts at the scene of the devastation early Tuesday, with fears that the ruins of a two-storey residential building would collapse.

Foreign Minister Adnan Mansour confirmed on Monday that two Lebanese were among the dead in the plane crash in Nigeria’s largest city.

One of the victims, a contractor, is from the Awad family, Mansour told Voice of Lebanon radio station (93.3).

More than 150 passengers are feared dead after their plane crashed in a densely populated district of Nigeria's economic capital Lagos Sunday, residents and an aviation official said.

Thick smoke was rising from the area, near Lagos airport, and flames could be seen coming from a two-story building.

A suicide bomber who tried to drive an explosives-packed car into a church in northern Nigeria on Sunday killed at least nine people, including himself, and injured 35, officials said.

The attacker sped his vehicle as he approached a checkpoint near the church in Bauchi State, which had heightened security following previous attacks in the area blamed on Islamist group Boko Haram.

Gunmen abducted an Italian engineer on Monday in Kwara State, central Nigeria, Italy's foreign ministry told Agence France Presse on Thursday.

"We can confirm an Italian engineer has been kidnapped. We don't yet know why or by whom," said the ministry spokeswoman. Italian officials were in contact with Nigerian authorities and the man's family, she added.

Gunmen on a motorcycle shot dead four traders from the mainly Christian Igbo ethnic group in northeastern Nigeria on Monday, residents said, the latest in a string of such attacks.

Islamist group Boko Haram has carried out scores of shootings and bomb attacks in northern Nigeria, but it was not immediately clear who was behind Monday's killings in the city of Yola, the capital of Adamawa state.

An American citizen has been kidnapped in the West African nation of Benin, a U.S. embassy spokeswoman said Saturday, but details of the incident were unclear.

"I can confirm an American got kidnapped in Benin last week," Melissa Ford, a spokeswoman for the U.S. embassy in neighboring Nigeria, told Agence France Presse, indicating she had no other details.

The fire burns and the smoke rises in this violence-torn Nigerian city, but the sweet smell that follows makes clear there is no reason to be afraid -- unless you are vegetarian.

"The people here have high culinary taste," 32-year-old Isa Jaja explained while trimming fat off a slab of beef at his food hut along a road where security forces in trucks regularly prowl, rifles at the ready.

An explosion rocked an area of the Nigerian oil hub city of Port Harcourt on Thursday, a military spokesman said, but the cause and extent of damage remained unclear.

"There was actually an explosion around Rumuokoro area of Port Harcourt," Lieutenant Colonel Onyema Nwachukwu said of the city in southern Nigeria that is home to a number of oil firm offices.