A U.S. official told CNN that a quick reaction force has been launched in an effort to rescue those forces on the ground in Marjah. The official could not say where the force was launched from or how many people were involved.
The service member who was killed came under fire as part of a train-and-assist mission in Marjah, located in Helmand Province, Pentagon Spokesman Peter Cook said.
Initially, two medivac helicopters were sent to provide assistance, according to Cook.
"One of those waved off after taking fire and returned safely to its base," he said. "The second landed safely, but sustained damage to its rotor blades after it apparently struck a wall."
He indicated that the second helicopter remains on the ground.
"This is still an ongoing situation," Cook said. "There is still a fight going on in the immediate surrounding."
He added, "I'm not aware of anyone who's unaccounted for" but that "I cannot say with certainty that every single member was, in fact, Special Operations forces on the U.S. side of things"
He concluded, "We don't have all the details surrounding what is taking place."
Cook's comments differ from initial reports from Defense officials, who said a medical helicopter was hit by mortar fire while on the ground but was able to take off.
Another military spokesman expressed condolences on the death of the U.S. service member.
"We are deeply saddened by this loss," said Brig. Gen. Wilson A. Shoffner. "Our heartfelt sympathies go out to the families and friends of those involved."
White House Press Secretary Josh Earnest said the President had been briefed on the ongoing situation in Afghanistan and the casualties sustained. "Obviously this does underscore that Afghanistan is a dangerous place," he said.
The U.S. service member killed in action and the wounded personnel have been extracted from the Marjah, Afghanistan site where they came under fire. There are still U.S. military personnel on scene there to secure the damaged helicopter, but they are not trapped or surrounded, the official said. Those personnel are from the quick reaction force that was sent to the site. There were four Afghans that were wounded that were evacuated as well.
Taliban fighters have made major inroads of late in Helmand, including taking over the key district of Sangin late last month, local police chief Mohammad Dawood said.
Mohammad Jan Rasolyaar, the deputy governor of Helmand province, around that time wrote an open letter to President Ashraf Ghani warning that the province could fall to the Taliban if the Afghan government didn't step up its efforts there.
The U.S. military has been a constant presence in Afghanistan since the weeks after the September 11, 2001, terrorist attacks, an effort that helped oust the then-ruling Taliban from power.
But while the Taliban no longer run things from Kabul, they've hardly gone away. The group has been blamed for regular bloodshed against Afghan forces and the U.S.-led coalition supporting them.
NATO handed over control of security operations to their Afghan counterparts in December 2014, with the U.S. military's combat mission in Afghanistan officially ending under President Barack Obama's watch.
Obama also signaled plans to withdraw American forces from the country, only to announce last October that U.S. troops will remain in the country at current levels throughout much of 2016.