A man has died after violence in the Lozells area of Birmingham on Saturday night. Four people were stabbed and two people shot in the disturbances.
The landlady of a local pub saw "people with sticks"
A black man in his 20s died from stab wounds and a police officer was shot with a ball bearing gun. The other injuries are not said to be serious.
A riot broke out after a public meeting in the area over an alleged sexual attack on a 14-year-old girl.
Police say the violence was not a reaction to the meeting.
Assistant Chief Constable David Shaw said: "It does not appear that a lot of people got together in advance, but I do believe that some people started the day, with intent to cause mayhem."
He added: "Police and community leaders share their abhorrence with the loss of life experienced.
"This is the work of a small number of individuals and is not a true reflection of community relations in Birmingham."
Some locals say a 14-year-old illegal immigrant was subjected to a serious sexual assault last Tuesday.
"There is an allegation that a young black girl has been raped, some people say gang raped, by some Asian men, and that is the core cause of the tension," Bishop Joe Aldred from the Council of Black Led-Churches, told BBC News 24.
Since then several people from the Afro-Caribbean community have been "campaigning for justice" outside a shop where the attack allegedly took place, he said.
Bishop Aldred said the meeting was held to shed some light on the issue.
"I think that the violence was linked to the tensions there have been in the community since maybe Tuesday," he said.
"It could not have been linked to the church meeting because what came out of that was the kind of stuff that would allay fears, not heighten them."
Police say they are following several lines of inquiry and have carried out forensic tests, house-to-house inquiries and distributed thousands of leaflets in a bid to find the alleged victim.
The Home Office has promised it will not investigate the victim's immigrations status until after the end of any criminal proceedings.
Mr Shaw said there was "not a shred of evidence" to support the allegations but investigations were continuing.
He said: "Birmingham is a city that prides itself on living together harmoniously with one another and has done a fantastic job for many years when other places have been challenged.
"We have to ask ourselves really searching questions now about how we can prevent our community that we so cherish being characterised by these events."
A police spokeswoman said the dead man would not be named until next of kin had been informed. A number of arrests have been made.
HISTORY OF TENSION
The Lozells area has a history of racial violence
Tension exists between the large Afro-Caribbean population and Asian gangs
Drugs and gun crime are also major causes of trouble
In 2002 a female Asian shopkeeper was attacked with a machete by a black man
In 2003, Charlene Ellis, 18, and Letisha Shakespeare, 17 were shot dead in nearby Aston as the Burger Bar Boys gang sought revenge on rivals the Johnson Crew
The area also saw the September 1985 Handsworth riots, triggered by the arrest of a black man after a police stop and search
A spokeswoman for West Midlands Ambulance Service said at least 12 people had been taken to the City Hospital in Dudley Road in Birmingham.
Police officers in riot gear, dog handlers, fire engines, ambulances and vehicle recovery units patrolled streets in the area.
The confrontation between rioters and police saw cars burned, missiles thrown and groups of people wearing masks, or covering their faces with hoods.
A burnt-out wreck of a car was left abandoned outside the Asian Resource Centre in the middle of Lozells Road.
Bricks were also scattered across the road outside the New Testament Church of God where Saturday's meeting was held.
BBC correspondent Deborah Bain said the riots broke out after about 100 people outside the meeting started fighting with the police.
But she said it was "not yet clear what sparked the disturbances which came without warning".
The meeting in a local church in Lozells Road, which was addressed by two senior police officers and the MP for Perry Barr, Khalid Mahmood, followed an earlier rally of about 200 people in support of victims of crime.
Mr Mahmood told BBC News he thought the incidents were linked to the assault allegation but a small group of people "predominantly from outside the area" were responsible.
"There are a very small number of individuals who are carrying out this," he said. "They're a fairly mobile group of people."
The rally was in support of victims of crime
"There's been about four or five flashpoints in different parts of the Aston Handsworth ward and what we are trying to do is to deal with that."
Mr Shaw said he paid tribute to the work carried out by the local black and Asian community to reassure people and "try and put some fact behind the rumours".
A statement on the force website said the build-up to the violence started last weekend.
"Police treated this as serious and have investigated it as if a crime had taken place but despite this there has not been any evidence that an attack has taken place."