An eruption began in the summit caldera of Hawaii’s Mauna Loa, the world’s largest active volcano, on Sunday night, the U.S. Geological Service’s volcanic activity service said.

“At this time, lava flows are contained within the summit area and are not threatening downslope communities,” the notification said.

The volcano alert level was upgraded from an “advisory” to a “warning.”

The Hawaiian Volcano Observatory will conduct aerial reconnaissance to better describe the eruption and assess hazards, the notification added.