 -- Ten additional cases of Zika virus infection have been reported in northern Miami, leading to fears of a growing outbreak of the disease, according to government officials. Florida Gov. Rick Scott has activated the emergency response team from the U.S. Centers for Disease Control and Prevention to help stem the outbreak.

Four people were confirmed last week to have the virus after likely contracting the disease via infected mosquitoes in a 1-square-mile area in northern Miami, according to Scott. The outbreak is the first time the Zika virus has been transmitted via infected mosquitoes within the continental U.S.

Today the Florida Department of Health "has confirmed that 10 additional people have contracted the Zika virus locally, likely through a mosquito bite," Scott said in a statement. "DOH has been testing individuals in three locations in Miami-Dade and Broward counties for possible local transmissions through mosquito bites. Based on DOH's investigations, two locations have been ruled out for possible local transmissions of the Zika virus."

Of the 10 additional people reported infected, six had no symptoms and were identified only through a door-to-door investigation. Experts from the CDC and National Institutes of Health had long suspected that there could be some local transmission of Zika virus in the U.S., especially in Florida, where the Aedes aegypti mosquito is present and many people travel to South or Central American countries, where the Zika epidemic has been ongoing.

The Florida Department of Health has tested 2,300 people for Zika virus statewide, and 372 have been confirmed to be infected with the virus.

Scott tried to reassure residents by pointing out the state dealt with previous mosquito-borne outbreaks, like dengue and Chikungunya.

"Florida has a proven track record of success when it comes to managing similar mosquito-borne viruses," Scott said in his statement. "We will continue to keep our residents and visitors safe utilizing constant surveillance and aggressive strategies, such as increased mosquito spraying, that have allowed our state to fight similar viruses. While I encourage all residents and visitors to continue to use precaution by draining standing water and wearing bug spray, Florida remains safe and open for business."

The CDC has now issued a warning to pregnant women to avoid unnecessary travel to the area affected in northern Miami.

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, said a larger outbreak of cases would force health officials to reassess not just new warnings for people traveling to the area but its advice for locals there.

"What do you then do about pregnant women who both reside and work in that area?" he told ABC News. "These are very, very hard questions."

Schaffner pointed out that health officials will have to be careful about how to advise people in the area even if they think the overall risk of being infected with Zika remains low as long as people don't spend a large amount of time outdoors.

"There are no absolutes here," he said. "I think at the bottom line, the risk of acquisition of Zika even today is very low."

White House deputy press secretary Eric Schultz said today that the president "is continually getting briefed on the situation in South Florida."

"A team is being deployed by the CDC in short order so that we will be able to work with Gov. Scott's team on the ground in South Florida," Schultz said, noting that the CDC has been budgeted $2 million in Zika-response funding and also $27 million in emergency preparedness funding, much of which can be used for Florida's Zika response.

Schultz said that Congress' decision not to fund further Zika prevention efforts had hindered the administration's ability to fund more research and slowed the development of an anti-Zika vaccine.