(CNN)Hillary Clinton appeared wobbly Sunday and stumbled as Secret Service agents helped her into a van to depart the 9/11 commemoration ceremony early.

The Democratic presidential nominee felt overheated, her campaign said, when she left at about 9:30 a.m. ET and traveled to her daughter's nearby apartment.

"Secretary Clinton attended the September 11th Commemoration Ceremony for one hour and 30 minutes this morning to pay her respects and greet some of the families of the fallen. During the ceremony, she felt overheated so departed to go to her daughter's apartment, and is feeling much better," Clinton spokesman Nick Merrill said in a statement.