The violence began on Sunday when a Christian church was attached by young Muslim gangs. Christian youths have returned since the favor. At least 20 people have been killed since Sunday, but medical professionals say that more bodies than that have been brought into area hospitals.
The majority of Nigerians are Muslim, but Christians make up 40 percent of the population.
From the BBC, we read more about the situation in Nigeria.
Extra troops have been deployed to the area, which has seen several bouts of deadly violence in recent years.
At least 200 people were killed in clashes between Muslims and Christians 2008, while some 1,000 died in 2001.
Houses, mosques and churches were set alight on Sunday.
At least 3,000 people have fled their homes, according to the Red Cross.
Residents say many buildings have been set on fire, especially in the northern parts of the city.
"As early as 4am (0300 GMT), we started hearing gunshots and machine-gun fire and this has gone on for hours," Dr Aboi Madaki, who works at the Jos University Teaching Hospital, told the Reuters news agency.
"I saw soldiers moving into town and I can see smoke coming from many places."
Jos is in Nigeria's volatile Middle Belt - between the mainly Muslim north and the south where the majority is Christian or follows traditional religions.
Correspondents say such clashes in Nigeria are often blamed on sectarianism, however poverty and access to resources such as land often lies at the root of the violence.