Boston Police have mounted an aggressive operation aimed at preventing a feared outbreak of gang violence at this weekend's Caribbean Festival in Roxbury and Dorchester. The department has already rounded up dozens of so-called "impact" gang members known to have violated conditions of their probation and have issued multiple "stay-away"orders to other young men they say are affiliated with warring gangs. The department will also step up its deployment of video surveillance teams in an attempt to discourage any gang associates from using the otherwise peaceful event to stage an attack on rivals.

Hundreds of thousands of people typically turn out for the annual "Carnival", which features colorful costumes, floats and large crowds which often walk and dance alongside performers and DJs on a route from Martin Luther King Boulevard to Franklin Park. Even under ideal circumstances, the rolling event is a huge logistical challenge for the city's services, which deploy hundreds of police officers, EMTs and other employees to assist in the day's festivities. Still, violence has marred the event in year's past. Last year, four people were stabbed in incidents connected to the event, according to Boston Police.

In an hour-long briefing held this afternoon at Boston Police headquarters, a group of about 50 senior officers reviewed photo arrays of suspected gang members who could pose problems tomorrow. A summary of field intelligence collected by local police districts clearly has the department's command staff worried that some groups intend to use the massive crowds at Saturday's events to cloak their retaliatory strikes. The parade and the after-parties that precede and follow it are "a historical day for payback and retribution by almost of gangs in the city of Boston," according to a slideshow prepared by the BPD's Boston Regional Intelligence Center.

Specifically, the BPD has received consistent tips that a feuding gang based in Mattapan could come under assault by two other gangs from the Norfolk-Morse Street areas who have combined forces to assault their rivals. The briefing said that an estimated "40 associates" could be prepared to target the Lucerne-Favre-Colorado street gang tomorrow in retaliation for past incidents.

"Unfortunately, we do have some individuals who use the cover of crowds to seek revenge," said Superintendent Daniel Linskey, the chief of the BPD's Bureau of Field Services, who led the briefing. "Our goal is to prevent that feeling of anonymity."

Captain James Claiborne, commander at district B-3, said his officers will be accompanied at their posts along the parade route with probation officers from West Roxbury and Dorchester courts to "reduce anonymity" among any gang members who do show up. Boston Police officers will wear bright green vests over their black uniforms to help maintain a high level of visibility, Linskey said.

Commissioner Edward Davis said tensions are high this year based on the intelligence reports that have been gathered in preparation for the annual parade over the last several weeks. Further ratcheting up fears of violence was an Aug. 9th shooting that left seven people wounded and one dead at Hartford's annual West Indian festival. A similar event in New Jersey was cancelled earlier this month because organizers could not raise enough money needed for police details, according to Boston Police.

"The small group of mostly gang affiliated have to be controlled," Davis told his command staff. "We have to balance enforcement efforts with restraint to allow people to come and enjoy this event. This is a cultural event that people are coming from all over the eastern seaboard to enjoy."

"We have special challenges this year, " Davis said. "We're going to have sufficient resources to deal with the threat."

Police will be taking pre-emptive steps tonight to monitor several licensed pre-Carnival parties at venues in Dorchester - including the Russell Auditorium - and elsewhere in the city. They are also tracking several other unlicensed parties that have been advertised online and through fliers.

Assisting the Boston Police in their preparations this week are two police officials from Northern Ireland, whom Davis described as "the single best experts" on crowd control tactics in the world. Chief Inspector Andrew Galbraith and Asst. Chief Constable Duncan McCausland attended the briefing on Friday afternoon. Davis said that they shared ideas on how to better use video surveillance of the crowds as a form of control and, possibly, for future arrests. Boston Police will deploy their own teams of videographers tomorrow - and use tapes taken from MBTA cameras mounted inside and outside of T buses - to look for possible criminal activity.

"There will be legal action taken - and in some cases well after the fact - to anyone who acts out at this event," said Davis.

Davis said he personally reached out to the Police Service of Northern Ireland to seek outside advice after the death of 22 year-old David Woodman, who was being forcibly detained by Boston Police when he stopped breathing on June 22.

"Because of the incident that occurred, I felt it was very important to reach out," Davis said. "We've been able to come up with some really good ideas for this process and for future events."

The Caribbean parade begins on Saturday at 1 p.m. at Warren Street and Martin Luther King Boulevard in Roxbury. The parade is scheduled to end at 6 p.m.