A day care center at Fort Myer was evacuated Thursday after a reported "carbon monoxide incident," said Arlington County Fire officials.
Several patients were evaluated but not taken to hospitals, fire officials said.
The problem was determined to be a natural gas leak, officials announced Thursday afternoon.
"Professionals isolated the problem and will continue to monitor the situation through the night," a statement said.
The center will be open as usual on Friday, officials said.
A suspicious odor was detected late Thursday morning at the Cody Child Development Center in the Fort Myer portion of Joint Base Myer-Henderson Hall (JBM-HH) in Arlington, Virginia.
Children were moved to another portion of the center while JBM-HH Fire and Rescue services investigate.
Parents were notified and asked to pick up their children as soon as possible.
"Our primary concern is the safety of everyone involved," Col. Mike Henderson, JBM-HH commander, said in a statement. "We are doing everything possible to mitigate any potential danger to children, staff and others involved."
Parents who need information are advised to call the JBM-HH commander's information hotline at 703-696-6906.