The traumatised girl, one of five children, is of Western Samoan descent. Her attackers, she told police, were youths of African appearance who pinned her to the ground and assaulted her over 30 minutes. For a week, leaders of both communities have been worried about crude threats of reprisals circulating through social media.

''Nigga I no who you are now. Just dnt no what to decide to do with ya yet you mut'', reads one threat from a member of the girl's extended network.

The women, too, are worried about the threat of paybacks.

''We hope the police get the offenders fast … before our boys get to them'' one says, shaking her head. ''Some [islanders] have already been round here saying 'just give us the word and we will do it'.''

On Friday, police announced their first breakthrough in the case. A 16-year-old Sudanese-born boy, one of several thousand Sudanese living in the Blacktown area, was charged with sexual intercourse without consent. He had handed himself in on Thursday evening. He cannot be named, but his Facebook profile shows him to be a keen soccer player and part of a large family in Blacktown. He and the alleged victim had attended the same school and there appear to be connections between some of his friends and the girl's older brother.

One source said the youth was ''getting support from people because he's young, he's scared'' and that his parents were devastated. With the police now hunting four others, many are worried about who could be next.

Community leaders hope the arrest will send a clear signal that the matter is best left in the hands of the authorities. At a hastily convened meeting earlier in the week, prompted by media coverage, the new police commander for Blacktown, Superintendent Gary Merryweather, youth leaders, school principals and social welfare agencies discussed how to get the message out that the alleged crime was not a race crime.

''There is not more of race crime here than anywhere else'' says Susan Vogels, chief executive of migrant services organisation SydWest. ‘‘It’s just that Blacktown seems to be an easy hit, we get the reputation for it, and it’s very wearing because of all the work we are doing to ensure social cohesion.’’

One immediate outcome of the meeting was the resumption of the ‘‘harmony walks’’ begun by Superintendent Merryweather’s predecessor, Mark Wright, several years ago, when regular fights were flaring between bored young men from rival ethnic groups in the Blacktown area. On Thursday, local police set out on foot with high-profile leaders from the African and Pacific Islander communities, weaving through places frequented by youngsters.

Mayor Chagai, a former refugee from Sudan who runs basketball teams for African and other teens at the local Police Citizens Youth Club, insists ‘‘there is a lot of good commitment from communities on both sides to defuse this situation’’.

‘‘The kids here love playing together, we spoke with them about just taking care of themselves, avoiding any group that is trying to incite any cultural tension or anything like that,’’ he says.

The same message has gone out through local schools, one of which is only a few streets away from the scene of Saturday’s attack.

Sudanese-born lawyer Deng Thiak Adut, who joined Thursday night’s walk, said the situation appeared to be calm but he remained worried about young men who might be walking home alone after late-night shifts at fast food outlets.

There is little public transport and many do not have cars.

He complained, too, that some reporting of the issue had inflamed tensions.

‘‘It incites other communities to look at us as lesser beings in this country,’’ he says. ‘‘No community owns a criminal – this crime was not committed by a community.’’

Comments from state Communities Minister Victor Dominello, who told an audience on Thursday that news of the incident had contributed to his feeling that ‘‘we may not be the best country on earth’’, have not been seen as helpful by those working hard to contain the fallout.

Blacktown is the most heavily populated local government area in NSW. Its nearly 320,000 residents come from 184 different national and ethnic backgrounds. An estimated quarter of them are aged under 18. Some fleeing Syria’s carnage are starting to find their way to Blacktown.

‘‘They come from wherever the trouble spots in the world are,’’ says Ms Vogels, ‘‘and we try to assist them to become good, functioning citizens.’’

But she admits agencies like hers are ‘‘running on the smell of a greasy rag and that rag is getting less and less oil on it’’.

Two teenage Sudanese boys who spoke to Fairfax Media behind a basketball court in Blacktown on Thursday evening said their weekends were consumed by drinking and fighting, although race was not always the catalyst.

‘‘It’s all about who your boys are,’’ said Deng, 16, whose surname has been withheld. ‘‘You gotta defend the area. You gotta defend the honour of Blacktown.’’ Adam, 17, says: ‘‘There’s Bloods, Crips, Lalor Park boys, Bidwill boys.’’

Deng was recently charged with assault after a man racially taunted him at Blacktown station. The pair said they felt continually targeted by police.

‘‘People think they can be racist to Africans and expect nothing to happen,’’ Deng says. ‘‘Some guy arced up at me the other day, saying ‘nigger, nigger’, so I walked up and pushed him and then I got charged by the cops.’’

Adam, a talented rugby league player, was recently dropped from a representative team after returning a positive drug test.

Father Chris Riley, who runs Youth Off The Streets, says: ‘‘Right across western Sydney, we have a locked-out underclass of young people who don’t have the job opportunities, don’t have access to education. Each community has its own issues. With African refugees, we’re often dealing with people from war-torn countries ... who come with incredible post-traumatic stress that we don’t fix.’’

While his organisation has recently had an injection of federal funds, many of western Sydney’s other agencies have been forced to shelve or trim social support services since the change of government. Funds promised by Labor have been withdrawn by Justice Minister Michael Keenan, who says he prefers channelling money into the Coalition’s ‘‘safer streets’’ program, which is focused on better CCTV and street lighting.

Among programs to have suffered is the ‘‘Comm4Unity’’ program in Blacktown, which runs singing and dancing competitions for young people at the Westpoint shopping centre, allowing hundreds of youths from different ethnic backgrounds to mingle and make friends.

On Wednesday, Fairfax visited Bill Colbourne Reserve, the Doonside park where the 14-year old encountered her alleged attackers. After so little rain, it was a dispiriting sight – with concrete paths cutting through deadened grass, a scattering of native trees and a semi-derelict children’s playground.

In the park, four police officers were questioning a 15-year-old boy, the son of 40-year-old Asunta, who came from South Sudan seven years ago. She stood nearby, agitated, carrying a four-month-old on one hip. She has 10 children and it is hard, she says, to keep the older boys at school.

She too is worried about last weekend’s attack.

‘‘Maybe someone do something but it is just the one – not all my country,’’ she says.