About 3,500 acres of southern Arizona along the Mexican border is closed to U.S. citizens due to increased violence in the region.

The closed off area stretches 80 miles along the border and includes part of the Buenos Aires National Wildlife Refuge. It was closed in October 2006 "due to human safety concerns," the U.S. Fish and Wildlife Service said Wednesday in response to news reports on the closure.

Pinal County Sheriff Paul Babeu told Fox News that violence against law enforcement officers and U.S. citizens has increased in the past four months, further underscoring the need to keep the 80 miles of border land off-limits to Americans.

The refuge had been adversely affected by the increase in drug smugglers, illegal activity and surveillance, which made it dangerous for Americans to visit.

"The situation in this zone has reached a point where continued public use of the area is not prudent," said refuge manager Mitch Ellis.

“It’s literally out of control,” said Babeu. “We stood with Senator McCain and literally demanded support for 3,000 soldiers to be deployed to Arizona to get this under control and finally secure our border with Mexico. “

U.S. Fish and Wildlife officials have warned visitors in Arizona to beware of heavily armed drug smugglers and human traffickers.

“We need support from the federal government. It’s their job to secure the border and they haven’t done it,” said Babeu. “In fact, President Obama suspended the construction of the fence and it’s just simply outrageous.”

Signs have been posted warning Americans not to cross into the closed off territory south of Interstate 8. Babeu said the signs are not enough – he said Arizona needs more resources to help scale back the violence caused by the drug cartels.

“We need action. It’s shameful that we, as the most powerful nation on Earth, … can’t even secure our own border and protect our own families.”