The explosion struck the town of Sabon Gari at around 1.30 p.m. (1230 GMT), the sources said.
Hundreds have been freed from Boko Haram captivity this year but none of the 219 girls abducted in April 2014 from a school in Chibok were among the rescued.
There was no immediate information on the number of victims, although witness accounts suggest that there were casualties.
Many Boko Haram militants were killed in firefights with Nigerian soldiers in villages near the northeastern city of Maiduguri
Monday’s was the latest in a spate of attacks that have killed hundreds in recent weeks and spilled across Nigeria’s borders.
The first explosion took place outside a packed footwear shop around 0950 IST on Thursday, followed by a second explosion just minutes later, said Badamasi Amin, a local trader who counted at least three bodies.
There was no immediate claim of responsibility for the blasts but Jos has been repeatedly attacked by the Boko Haram Islamist group.
Boko Haram militants stormed three remote villages, kill residents and set houses ablaze in the bloodiest day of attacks by the group since President Muhammadu Buhari came to power.
The Nigerian army said that Babuji Ya’ari was actively involved in the mass abduction of schoolgirls in Chibok and his arrest led to arrest of some female members of Boko Haram.
The rebels shot dead their victims after looting homes and shops and setting fire to buildings, said Debiro Hawul resident Umaru Markus.
Two teenage girls blew themselves up near a crowded mosque in Maiduguri, killing 30. This is the fourth suicide attack in June by Boko Haram.
Boko Haram took control of a large swath of northeast Nigeria until a multinational force this year forced them out of towns and villages.
Local authorities say the victims probably died several months ago and their remains have only now come to light.
Nigeria police said four other people were injured in the attack.
The explosion was timed to go off as merchants were closing shop, others were hurrying to make last-minute purchases and commuters were catching tricycle taxis home.