Red-hot lava began flowing from the crater of Indonesia's rumbling volcano Mount Merapi early Thursday as vulcanologists warned residents an eruption may be imminent.

Burning streams of molten lava started pouring down the slopes at about 2 a.m. local time, said Subandriyo, the chief of Merapi's Volcanology and Monitoring offices, who goes by a single name.

Residents still near the 9,700-foot peak were urged to leave immediately, even though officials said they were not yet raising the alert to the highest level.

"The volcano has shown significantly more activity," Subandriyo said.

Merapi is one of at least 129 active volcanoes in Indonesia, part of the Pacific "Ring of Fire" — a series of fault lines stretching from the Western Hemisphere through Japan and Southeast Asia.

It last erupted in 1994, sending out a searing cloud of gas that burned 60 people to death. About 1,300 people were killed when it erupted in 1930.