Nigeria’s health minister has declared a health emergency as the deadly Ebola virus gained a foothold in Africa’s most populous nation, according to news reports.

“This is a national emergency. Everyone in the world today is at risk. The experience of Nigeria opens the eyes of the world,” Minister of Health Onyebuchi Chukwu told the country’s House of Representatives.

Nigerian authorities moved quickly late Wednesday, gathering isolation tents as five more cases of the Ebola Virus were confirmed in Lagos, a city bursting with 21 million people.

All five people are believed to be health workers who had direct contact with one man traveling from Ebola-ridden Liberia to Nigeria — making this country the fourth now infiltrated by the deadly disease.

The World Health Organization meanwhile convened to discuss whether the crisis warrants a global health emergency, BBC News said, as the virus grips Guinea, Liberia and Sierra Leone and, now, Nigeria.

Forty-year-old Patrick Sawyer, a Liberian-American civil servant on a business trip to Nigeria two weeks ago, reportedly collapsed upon arrival at Lagos’ main airport. On Tuesday, State Health Commissioner Jide Idris said the man was diagnosed with the disease and died after he had been taken to a local hospital.

A nurse who treated him reportedly died Wednesday. “Yesterday the first known Nigerian to die of Ebola was recorded,” Chukwu told reporters in Abuja on Wednesday. “This was one of the nurses that attended to the Liberian. The other five [newly confirmed] cases are being treated at an isolation ward.”

Idris said this is the time “for everyone to be vigilant, especially with regard to relating to people who are ill.”

According to local news reports, Nigerian authorities first downplayed the risk of exposure. Then on Tuesday, Idris disclosed that the infected man had come into some sort of contact with at least 70 people — airline passengers, airport workers and healthcare professionals — all of whom have been placed under surveillance. Seven have been quarantined, he said.

The WHO meeting was expected to last two days. If an international health crisis is declared, it could come with travel and trade restrictions, AP said.

The U.S. Centers for Disease Control and Prevention issued its highest-level alert Wednesday concerning the crisis in West Africa. “Level 1 activation” is reserved for the most serious public health emergencies, and the agency said the move was appropriate considering the outbreak’s “potential to affect many lives.”

The CDC took a similar move in 2005 in the aftermath of Hurricane Katrina, and again in 2009 during the bird-flu threat.