During a predawn sweep, 43 agents took nine alleged members of the Sureños gang into custody, charging them in connection with a December double fatal stabbing in southern Chester County.

The arrests of defendants ranging from ages 16 to 20 took 87 minutes, and they were accomplished "without incident," according to Chester County chief detective James Vito, one of several members of law enforcement who spoke at a news conference Monday afternoon. A 10th defendant who was charged was already in custody for an unrelated incident.

District Attorney Tom Hogan said the fatal attack on Cuahuctemoc Bedolla, 27, and Jose Rodriguez, 29, both of West Grove, was preplanned and brutal. He said a group of Sureños, also known as Sur 13s, was asked to leave an outdoor bonfire in New Garden Township on Dec. 3 because associates of the Vikings, a rival gang, were already present.

Hogan said the group complied but returned with reinforcements and weapons - knives, bats, bottles, and sticks - about an hour later. He said the 12 Sureños divided up into two groups so they could ambush the victims from two sides to prevent escape.

The stabbing was so violent that one of the defendants got his knife stuck in one of the victims, Hogan said, likening the grisly scene to The Sword in the Stone.

James L. Jones, 19, and Stephen Andrew Daddezio, 17, both of West Grove, were charged several days after the homicides.

On Monday, charges of varying degrees related to the fatal stabbings were lodged against the following defendants: Manuel "Mongo" Mora, 20, of Kennett Square; Junior Lopez, 18, of Avondale; Jorge L. "Borrega" Ramirez, 19, of Avondale; Dominick Daddezio, 17, of West Grove; Orlando V. "Pitufo" Diaz, 17, of West Grove; Cristian Eumana, 18, of Greenville, Del.; Kenneth Fitzsimons, 20, of West Grove; Fabian "Macaco" Cortez, 20, of Kennett Square; Rafael "Rafa" Lopez, 19, of West Grove; and Edwin "Barrill" Romero, 16, of Kennett Square.

Assistant District Attorney Andrea Cardamone, who will be prosecuting the case with Assistant District Attorney Christopher L. de Barrena-Sarobe, said a preliminary hearing was scheduled for Friday.

Cardamone said the exact cause of the fight was not known, but she said "ongoing animosity" between the two groups had existed since 2000. She said people generally understood that "if they're at the same place, there's going to be trouble."

People in law enforcement who have studied gang activity in southern Chester County said the members represent a small proportion of the Hispanic population and generally succeed in staying below the radar.

Hogan credited the success of the investigation to collaboration between county agencies such as the County Detectives and Sheriff's Department with federal, state, and local groups, including the Department of Homeland Security, state police, and New Garden Township Police. Hogan said he could not elaborate on the role of federal agents but said they would have to answer any questions about the defendants' immigration status.

He said he hoped the raid sent a clear message to gang members who want to reside in the area.

"Any gang that comes to Chester County will be dismantled," he said.

The investigation is continuing, Hogan said. Anyone with information is asked to call New Garden Township Police at 610-268-2907, or the Chester County Detectives at 610-344-5100.

Contact staff writer Kathleen Brady Shea at 610-696-3815, kbrady@phillynews.com, or @brandywinebits on Twitter. Read her blog, "Chester County Inbox," at www.philly.com/chescoinbox