STORY: The organization's Hawaiian Volcano Observatory (HVO) detected a glow in Kilauea summit webcam images on Wednesday at 4:44 a.m. (14:44 GMT), indicating a new eruption.
"The opening phases of eruptions are dynamic," the USGS said in an advisory. "The activity is confined to Halemaʻumaʻu (crater) and the hazards will be reassessed as the eruption progresses."
The USGS said it is elevating Kilauea's aviation color code from orange to red as it evaluates the eruption.
Located in a closed area of Hawaii Volcanoes National Park, Kilauea is one of the world's most active volanoes.
Kilauea last erupted in January, with activity stretching into March, the USGS says.