Big Island, Hawaii - Kilauea volcano on Hawaii's Big Island began erupting on Wednesday, with rock fragment projectiles hurling, the US Geological Survey (USGS) said.

"A line of low lava fountains is erupting from the crater floor, tephra is falling downwind, and a new fissure opened up on the west wall of Halema'uma'u crater," the agency said around 6 PM local time on Wednesday.

About an hour earlier, the agency tweeted that the eruption was "in full swing."

"What was once a cooling lava lake is now a new fissure eruption," the USGS said in a tweet, accompanied by images of the before and after.

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The volcano began erupting at about 3:20 PM local time, the report said, adding that the Hawaiian Volcano Observatory (HVO) "detected glow in Kilauea summit webcam images indicating that an eruption has commenced within Halema'uma'u crater in Kilauea's summit caldera, within Hawai'i Volcanoes National Park."

The USGS added that webcam imagery showed fissures at the base of the crater "generating lava flows on the surface of the lava lake that was active until May 2021."

The HVO elevated the volcano's alert level from "watch" to "warning" and its color code from "orange" to "red" as it monitored hazards associated with the eruption.

"The activity is confined to Halema'uma'u and the hazards will be reassessed as the eruption progresses," the USGS said.

Kilauea is considered one of the world's most active volcanoes. It attracts tourists who travel to Hawaii to watch red-hot glowing lava flow into the Pacific Ocean.