Casualties have been reported in an active shooter incident at the Fort Stewart U.S. Army installation in the state of Georgia, Fort Stewart said in a Facebook post on Wednesday.

"The installation was locked down at 11:04 a.m. and law enforcement is on the scene," it said, adding the incident took place in the 2nd Armored Brigade Combat Team area.

No further information was immediately available, including on the number of casualties and their severity.

“We are currently assessing the situation but we can confirm an active shooter,” Lt. Col. Angel Tomko said.

A post on Fort Stewart's Facebook page told all personnel in the locked down area to “stay inside, close and lock all windows and doors.”

Located about 64 kilometres southwest of Savannah, Fort Stewart is the largest Army post east of the Mississippi River. It's home to thousands of soldiers assigned to the Army's 3rd Infantry Division and family members.

“Due to the lockdown status all gates on Fort Stewart are currently closed,” the fort said on social media.

Georgia Gov. Brian Kemp is in contact with responding law enforcement, he said in a statement. US Rep. Buddy Carter, whose district includes Fort Stewart, said in an online post that he's monitoring the shooting.