It's a rite of passage for the young men: Maim or kill a rival gang member, according to prosecutors.

In the case of one North Texas MS-13 cell, that meant using shotguns, sledgehammers and even machetes — their weapon of choice, prosecutors said. On Friday, federal authorities in Dallas announced the arrests of seven local MS-13 gang members and associates on charges that include racketeering, attempted murder and assault with a dangerous weapon.

An eighth member is still wanted, the U.S. attorney's office said.

MS-13 is one of the largest street gangs in the U.S., according to federal authorities. One of its mottos is "Kill, steal, rape, control," according to the 18-count indictment unsealed Friday. The indictment says the gang's members are composed primarily of immigrants or descendants of immigrants from El Salvador.

Gang members and associates are required to commit acts of violence to join and maintain discipline. A principal rule is that they must attack and kill rivals, known as chavalas, according to the indictment.

The gang stands out due to its extreme and sensational violence. Gang members, for example, have filmed the torture and murder of young women. In other cases, gang members ran over their victims in vehicles, cut off their hands and hacked them to death with machetes.

Erin Nealy Cox, U.S. attorney for the Northern District of Texas. (Tom Fox/The Dallas Morning News) (Tom Fox / Staff Photographer)

One of the various branches or "cliques" operating in Texas is called the Irving Loco Salvatruchas, officials say.

And its members embarked on a violent spree across the Dallas area over several months, said Acting Assistant Attorney General John P. Cronan.

U.S. Attorney Erin Nealy Cox, of the Northern District of Texas, called the gang's methods "cold and calculating and ruthless."

"They actively recruit members, including juveniles, from our communities and from communities with a large number of immigrants from El Salvador and Central America," she said. "Their trademark is violence."

MS-13 has garnered headlines in recent months, and not only because of their violent tactics. The politics of immigration also has played a role.

President Donald Trump in May called the gang "violent animals" at a roundtable discussion on sanctuary cities and illegal immigration. "These aren't people," he said.

Critics have said Trump is using the extreme violence of MS-13 to stir anti-immigrant sentiment and seek a broader agenda of restricting immigration.

Gang experts say the extent of MS-13's influence in American cities is exaggerated.

Michael Paarlberg, an assistant professor of political science at Virginia Commonwealth University, said MS-13 does not have many members or much money, and there is no central leadership structure. The gang members are mostly teenagers or very young adults in a network of small gangs, he said.

"I do think this issue is highly politicized and exaggerated," he said. "The current administration wants to tie immigration to crime... it makes for a convenient boogeyman."

In Texas, the gang's membership has fallen to about 500 members, or less than 1 percent of the state's estimated 100,000 gang members, according to the Texas Department of Public Safety's annual gang assessment that was released last year. By comparison, Tango Blast and its associated cliques is estimated to have 19,000 members in Texas, the report said.

"MS-13 remains the most encountered gang illegally crossing the Texas-Mexico border in the Rio Grande Valley, though the number has decreased slightly since the border influx of illegal aliens in 2014," the state gang report said. "Although law enforcement actions in Houston and Dallas have had an impact on the gang's activities in those cities, the threat of this violent gang still causes concern for public safety."

An FBI official in New York said last year that the bureau believes there are up to 10,000 members of MS-13 currently living in the U.S.

Nealy Cox said it's difficult to say how rampant MS-13 gang activity is in the Dallas area, but that her office has several ongoing investigations into the street gang.

The Dallas area conspiracy began around July 2016, she said. The defendants launched at least six attacks in public areas of North Texas against rival gang members, including those from the 18th Street gang, which also has members from Central America, the indictment says.

Ten victims were seriously injured in the attacks, Nealy Cox said.

U.S. Attorney Erin Nealy Cox, center, holds a news conference on Friday, July 13, 2018 in Dallas. Federal prosecutors say eight MS-13 members have been indicted in Texas on charges tied to alleged gang activities including racketeering conspiracy, attempted murder and assault. (Vernon Bryant/The Dallas Morning News) (Vernon Bryant / The Dallas Morning News)

Many of MS-13's crimes were committed in public parks in Dallas and Irving, the indictment says.

In one case, an Irving park was the site of a shotgun and machete attack against four victims, according to federal authorities. Other members allegedly used a metal bat and knives in attacks. The gang also met in several Irving parks and in a tunnel under the city, the indictment says.

The gang used Facebook to plot the murders of rivals, the indictment says. And they marked their territory using graffiti that was spray-painted in July 2016 in Rose Meadows Park in Irving, the indictment says.

The Dallas indictment says MS-13 raises money by extorting businesses in its territory and through robberies.

The following were charged in the indictment: Rolan Ivan Hernandez-Fuentes, 25; Jerson Gutierrez-Ramos, 20; Cristian Wilfredo Cabrera-Cruz, 26; Kevin Cruz, 19; Jose Armando Saravia-Romero, 19; Manuel Amaya-Alvarez, 21; and Jonathan Alexander Baires, 20.

The U.S. attorney's office in Dallas provided these photos during a press conference announcing that a federal grand jury indicted eight alleged MS-13 members in Dallas on charges including racketeering conspiracy, attempted murder and assault with a dangerous weapon. (Vernon Bryant/The Dallas Morning News) (Vernon Bryant / Staff Photographer)

Attorneys for the men could not be reached for comment.

A Homeland Security Investigations official said all of the defendants are in the U.S. illegally.

Paarlberg, whose research includes U.S. immigrant communities, said MS-13 uses "petty street extortion" to fund their activities, and they are motivated by personal grudges. He said the gang has not been growing, and he cited one estimate that it is responsible for about 35 murders per year, which he called a comparatively small number.

Other street gangs, he said, are far more dangerous. But MS-13's use of machetes is "designed to be gruesome."

"They use spectacular violence to inflate their reputation and scare their enemies," Paarlberg said. "They want the reputation of being the biggest and the baddest, which they're not."

Nealy Cox said the defendants face lengthy federal prison time if convicted, including life behind bars. She said the government will use "every tool in our toolbox" to target violent gang members.

"We will not allow these violent gangs to continue to terrorize our communities," she said.

Katherine Greer, deputy special agent in charge of Homeland Security Investigations in Dallas, said the arrests will make other MS-13 gang members "a lot more cautious about operating in the open."

"Criminals who plan and attack others with machetes do not belong in a free society," Greer said.

Texas Gov. Greg Abbott said the state will continue offering help and resources to "crack down on these criminals."

"Evil gangs like MS-13 are perpetrators of senseless violence in our communities," he said.

Dallas District Attorney Faith Johnson called the gang a "threat to the peace and the dignity" of the local community. "We are committed to working together," she said.

Dallas and Irving police contributed to the investigation.

"The Dallas Police Department has long worked with area agencies to combat gang violence," Dallas Mayor Mike Rawlings said in a statement. "While any MS-13 presence in our region is troubling, the public should know that this is not a threat our Dallas police officers are currently encountering on a regular basis."