The International Committee of the Red Cross (ICRC) said that people have been sheltering in colleges, hospitals and schools since clashes began in the capital of the central Plateau state on Sunday.
More than 460 people in and around Jos are thought to have been killed as of Thursday.
Nigerian authorities relaxed a 24-hour curfew to allow thousands of residents whose houses have not been destroyed, to return home.
The strong presence of troops and police helped restore a measure of calm in Jos on Thursday.
But Andrew Simmons, Al Jazeera's correspondent in Abuja, said: "There has been a fresh outbreak of violence on the outskirts of Jos in a place called Bakuru.
"Six people have been treated for gunshot wounds. And a Red Cross [ICRC] official has confirmed that a woman was attacked by a gang who snatched her baby, twisted the baby's nose and broke it.
"We've had persistent reports saying gangs have been using police uniforms, knocking on door by door, masquerading as security forces and then killing people in their homes. It's a grim situation.
"But in Jos itself, the focus [on Thursday] was on the funerals of the hundreds of people who have been killed."
Earlier, Rob Waudo, from the ICRC in Kano, told Al Jazeera that since the military came in, the situation has been calm.
"[The arrival of soldiers] has allowed us to survey what the needs are. Many people have been able to leave the camps and return home," he said.
"There are so many people that need clothing, food and water. The Red Cross is focusing on those injured and referring some to hospital."Mosque officials have estimated the number of dead Muslims since Sunday to be about 400.
US-based Human Rights Watch (HRW) on Wednesday said at least 65 Christians had died.
Official government figures were significantly lower at 75 dead, more than 200 injured and 200 arrested.
HRW called for the Nigerian military to show restraint as additional soldiers were ordered onto the streets of Jos.
"Nigeria should ensure that its security forces use restraint and comply with international standards on the use of force in responding to the latest deadly outbreak of inter-communal violence," HRW said.
Charles Dokubo, from the Nigerian Institute of International Affairs, told Al Jazeera: "There is more than the religious aspect of it. There are two communities - one that call themselves settlers and one that call themselves indigenous communities.
"The crisis in the north started with the creation a local government."
Dokubo said Muslim settlers wanted to manage the government, which was unacceptable to the indigenous Christian community who regard the former as non-citizens.
"The main cause of the crisis is about administration and the place where people belong," he said.
The fighting erupted on Sunday in a Christian area due to a dispute over the building of a mosque, residents said.
Jos, which is home to 500,000 people, along with other central and northern areas in Nigeria have been plagued by religious violence in recent years.
In November 2008, hundreds of people were killed in Jos in two days of fighting triggered by a rumour that the mainly Muslim All Nigerian Peoples Party had lost a local election to the Christian-dominated People's Democratic Party.