Lagos, Nigeria - Sectarian violence between followers of Sunni and Shia Islamic sects in northern Nigeria has left dozens injured and many others arrested.
The violence in the northern city of Sokoto entered its fourth day on Monday. It began after reprisal attacks by Shias on Sunnis.
The Shias accused the Sunnis of molesting Shia women.
A spokesperson for Sokoto state, governor Attahiru Baffarawa, said the skirmishes were of "minimal magnitude", but residents said many people were injured and at least five houses were destroyed.
Local trader Sa'adu Labbo said: "A group of radical Shia followers launched an attack against a Sunni mob in the Marmaron-Garo area of the city on Thursday, for molesting a Shia woman.
"They said they would no longer condone assaults on their members.
"In the attack, the Shia followers destroyed three houses of those they accused of assaulting the Shia woman and injured a number of people."
He said the reprisals spread to other areas of the city, where attacks on Shias were reported.
Sokoto Shia community spokesperson Ibrahim Atiku, said "some overzealous" members of the sect took it upon themselves to seek out vengeance.
Atiku said: "This group has vowed to retaliate against any attack on any Shia follower from now on, because they can't fold their hands while they are being attacked, maimed and killed,".
Labbo and Atiku said the Nigerian police had made several arrests.
Clashes between Shias and Sunnis in the mainly Sunni town began in February last year, when a Sunni mob prevented Shias from attending Friday prayers at the central mosque in front of the sultan's palace.
The clashes left at least 10 people dead, with several houses and a Shia seminary destroyed.
Umar Dan-Maishiyya, a Sunni cleric accused of instigating the clashes, was arrested. He was released three weeks ago, after a year in police custody.
Atiku said: "We believe the renewed attacks on our members was caused by the release of Dan-Maishiyya, which emboldened the Sunni mob."