U.S. President Barack Obama speaks at the United Nations meeting on the Ebola outbreak in New York September 25, 2014. Reuters/Kevin Lamarque

World leaders pledged $1 billion to combat Ebola in West Africa and President Barack Obama called for a more urgent response against the outbreak that has killed thousands and stretched the resources of local governments during a United Nations meeting on the health care crisis Thursday in New York. More than two dozen world leaders participated in the meeting held during the General Assembly’s annual debate, including Guinean President Alpha Condé. Presidents Ellen Johnson-Sirleaf of Liberia and Ernest Bai Koroma of Sierra Leone joined by teleconference.

“We know from experience that the response to an outbreak of this magnitude needs to be both fast and sustained,” Obama said. “That’s only possible if every nation and every organization does its part. And everyone has to do more.”

Tony Banbury, who is leading the recently announced U.N. Mission for Ebola Emergency Response, or UNMEER, said the mission will deploy to the region Sunday and establish itself in the capitals of Sierra Leone, Guinea and Liberia, the hardest hit nations, throughout the week. He said 160 or so vehicles and some aircraft and helicopters will be allocated from other missions that are downsizing. WHO had previously pledged more than $350 million to fight the outbreak.

“The world can and must stop Ebola – now,” Secretary-General Ban Ki-moon. “We come together today in solidarity with the people of Guinea, Liberia and Sierra Leone as they face the largest and most deadly Ebola outbreak the world has ever seen.”

There are 6,263 known Ebola cases and 2,917 Ebola-related fatalities, according to the U.N. Health experts predict those numbers will rise exponentially unless the virus is contained and controlled. “This should not [be a situation] where there’s a lot of wrangling and people waiting to see who else is doing what. Everybody has got to move fast in order for us to make a difference,” Obama said.

Earlier on Thursday, Canada’s Minister of International Development Christian Paradis said he was frustrated over what he called an “inadequate” response from the U.N. and the international community. Canada pledged an additional $30 million to the $5 million or so it has already provided to fight Ebola.