Sunni and Shi'ite Muslims clashed in a town in Bahrain on Thursday, the first direct confrontation between the two sides since large scale protests erupted in the kingdom's main city two weeks ago.
Residents said a group of Shi'ites fought with a group of Sunnis and what they said were Bahrainis of Syrian extraction.
There were about a hundred people involved, one resident said.
Police helicopters circled overhead and two ambulances rushed from the scene. Youth with sticks and batons were also leaving the area.
The protesters camped out in the capital want political reform and better access to government jobs for the country's Shi'ite majority, which has long complained of second class status and discrimination. The government denies this.
The clash came on the same day that Bahraini opposition groups said they were now ready to enter into talks with the government without pre-conditions, but have sent a letter to the crown prince saying they want a new government and constitution.
A Sunni royal family rules the country of 1.2 million, half of whom are native Bahrainis, and a majority of those Shi'ite.
The protests in the capital Manama have been largely free of violence after police withdrew following an initial crackdown that killed seven.
The crowds, which also include some Sunnis, have been careful to avoid sectarian tones and instead stuck to calls for national freedom and unity.
Residents in Hamad said fighting died down when police forces arrived. Later there was a standoff between riot police and groups of Shi'ites who rushed to the area from other parts of Bahrain.
One man fell down and a large group came and beat him. There's still groups with sticks everywhere but fighting has largely stopped, one witness said.