The Irish Police have appealed for calm in the west Dublin suburb of Tyrellstown after a 15-year-old teenager was stabbed to death in a racist attack.

Friends of the murdered Toyosi Shittabey smashed windows of a car while returning from a rally that was held in honor of the teenager.

Several youths were restrained for attacking a group of teenagers that they believed to be associated with the murder.

Police spokesperson Supt John Gilligan has asked people in the area to "take a deep breath, take a step back and let the gardai (police) do their job." 

The suburb is one of the most ethnically diverse areas in the country, and Gilligan said there has never been racial tension in the area but described the stabbing incident as "truly exceptional."

Over 300 people attended a memorial at the sight of the stabbing.

A message of condolence from President Mary McAleese was read out at the rally.

The Nigerian ambassador Dr. Kemafo Nonyerem Chikwe also attended the rally.

Local MP Joan Bruton said the incident was out of character for the community and she praised the "excellent relation" between Irish and non-Irish nationals that reside in the area. Shocked local Fine Gael councilor Kieran Dennison said while this incident was rare, there was an undercurrent of racial tension. “Racism is something people have in their hearts.”

Bobby Huti is a friend of the victim and he told the Irish Times that the victim was subjected to "loads" of racist abuse in the past.

"This is were we live. He had been living here 11 years. We thought we were safe here. It is not like we went to some mad place where we weren't supposed to go. It has gone too far," said Huti.

Congo-born Patrick Kabangu said, "Racism is hiding everywhere. It is in the schools. Everywhere in Ireland is racist, it is just being hidden. This country is crazy."

Blanchardstown community liaison police officer Sgt. Vincent Connolly appealed for witnesses to come forward with information.

"I just wish to say to the people, if they have anything to say to us, please call us. We cannot do it without you."