A vicious drug war has come to the island home of 4 million Americans, which is being used as a transshipment point to the East Coast. NBC's Gabe Gutierrez reports.

SAN JUAN, Puerto Rico — The raids begin before dawn. Fierce knocks followed by shouts of “Policía!” rattle neighborhoods while a helicopter hovers overhead.

On this day in late September, heavily armed agents swarm otherwise peaceful-looking homes throughout the island.

In Toa Alta, outside of San Juan, one suspected drug trafficker surrenders without incident. Amazingly, no neighbors wander outside to see what’s going on. They must already know — or would prefer not to.

By 8 a.m., 16 people are in handcuffs, facing charges that include drug trafficking and money laundering.

The arrests are part of "Operation Overtime." U.S. Immigration and Customs Enforcement's Homeland Security Investigations special agents, working with officers from the Puerto Rico Police Department and San Juan Police Department, launched the initiative to combat drug trafficking in the Caribbean.

This is a war on American soil.

The murder rate in Puerto Rico is higher than in any U.S. state — and it’s roughly six times the national average. The island — best known for its stunning beaches and rich history — is home to roughly 4 million American citizens.

The island’s police superintendent, Hector Pesquera, told NBC News that more than two-thirds of the homicides are tied to the drug trade.

Luis Romero Font, 60, and his wife Marie Jane Rodriguez, 57, know the pain that comes with the incessant violence. Their son, Julian, was murdered during a robbery in April 2011.

He had just celebrated his 20th birthday.

Luis Romero Font and Marie Jane Rodriguez remember their son, who was killed last year in San Juan. Puerto Rico's murder rate is now roughly six times the U.S. national average.

"I try to focus my thoughts away from the negative, away from what I don’t have, and I try to remember what I did have,” his mother told NBC News. "That’s what sustains me."

'A hero had died'

Julian was stabbed to death as he walked down the street with his girlfriend. The robber cut him three times as Julian lunged to protect her.

"A hero had died," his father said, choking back tears. "I am very proud of him. I am very saddened … [by] this huge weight I have to continue bearing."

The teenager who killed Julian made off with his cell phone — a valuable tool that is often stolen for drug traffickers to communicate with each other.

In memory of his son, Romero Font, a telecommunications company CEO, has become an activist, starting his own group called "¡Basta Ya!" meaning, "Enough is Enough!"

"Puerto Rico cannot survive with this horrendous crime wave," he said.

Violent crime has been a part of life on the island for decades — ever since the 1980s when Colombian cartels began to thrive here.

But the last several years have seen a dramatic spike.

According to the Puerto Rico Police Department, there were 1,016 murders in 2010. That number rose to 1,136 in 2011.

Outgoing Gov. Luis Fortuno credits a police crackdown for reducing homicides in certain parts of the island by 22 percent so far this year. But he stresses it’s not enough.

He told NBC News that he feels ignored by the federal government and that he’s "banging on Washington’s door" for more help.

Federal agents and local police are cracking down on drug trafficking in Puerto Rico. NBC News speaks with an ICE agent and the island's recently appointed police superintendent, and tags along on a raid.

"We are American citizens," Fortuno said. "And we deserve to be protected."

Puerto Rico’s governor-elect, Alejandro Javier Garcia Padilla, was not immediately available for comment.

Earlier this summer, federal agents arrested dozens of workers at Puerto Rico’s main airport who had allegedly helped smugglers move cocaine to the mainland.

Drug seizures rising

According to ICE, agents have seized 22,000 pounds of illegal drugs so far this year. That’s up from 13,961 pounds in 2011 and 9,275 in 2010.

The street value of the recovered cocaine alone totals $250 million, ICE said.

Since Puerto Rico is a U.S. territory, once illegal drugs reach the island, they’re unlikely to face further U.S. customs inspections on their way to the mainland.

"I think the cartels are smart," said Rep. Michael McCaul, R-Texas. "They realize we're putting all of our efforts on the Southwest border (with Mexico) and we're not paying attention to the 'third border' — the Caribbean — so now they're exploiting that."

In June, McCaul chaired a hearing on Capitol Hill that focused on the increased drug smuggling in Puerto Rico.

"We have no strategy for the Caribbean," McCaul told NBC News. "There is no comprehensive plan."

He said that hopefully would change quickly as Washington learns more about the problem. In July, Homeland Security Secretary Janet Napolitano visited the island and promised to study the issue, adding that an increase in aid to Mexico did not come at the expense of the Caribbean.

A senior homeland security official told NBC News that since then, the department had conducted a comprehensive review of the situation in Puerto Rico and planned to focus on "quality over quantity."

The official, who asked not to be identified, said any future manpower surge would likely be "modest" and the department’s priority would be to increase efficiency among the officers already on the ground as well as resources outside the island — instead of simply pouring more money into the operations.

The increased cooperation would help prevent the flow of illegal weapons to the island as well as illegal drugs from the island, the official said.

Police department 'broken'

The drug-trafficking crackdown comes as Puerto Rican police fight to reclaim the trust of residents.

The 17,000-member force is the second largest in the United States. In a report last year, the Justice Department accused officers of engaging "in a pattern and practice of misconduct that violates the Constitution and federal law."

According to the DOJ’s findings, the department was "broken in a number of critical ways," including repeated instances of civil rights violations and illegal searches and seizures.

In 2010, the FBI arrested dozens of law enforcement officers on the island for allegedly providing protection to drug dealers.

Earlier this year, Hector Pesquera, the former head of the FBI's Miami division, was named superintendent of the Puerto Rico police. He told NBC News that weeding out corruption within his department has been a priority — and he’s seen progress.

"We have streamlined our procedures to work on the internal affairs cases,” Pesquera said. "We're getting rid of the backlog that existed. The word out there is clear: 'If you commit a transgression, you're going to be terminated.'"

For now, Pesquera said he and other Puerto Rican leaders are simply asking for a shift in federal resources. He said he realizes the difficult fiscal position the U.S. is in, but "we should not be begging for assistance."

Luis Romero Font, the activist who lost his son, agrees. He’s pushing the U.S. government to help stop the violence.

"When you lose a son, it’s like losing a huge part of yourself," he said. "Either [the U.S.] stops this now, or this crime wave will become something that infects Florida and the rest of the U.S. down the line."

So away from the tourists, the raids continue. America’s "third border" — the place known as the "island of enchantment" — remains at war.

More content from NBCNews.com:

Follow US news from NBCNews.com on Twitter and Facebook