Nearly 1,500 residents were ordered to evacuate from their volcano-side homes after Hawaii's Kilauea Volcano erupted, sending molten lava to chew its way through forest land and bubble up on paved streets.

Volcano officials couldn't predict how long Thursday's eruption may last, prompting Hawaii's governor to activate the National Guard to help with evacuations and provide security to about 770 structures left empty when residents sought shelter.

There were no immediate reports of injuries but at least 100 people were in shelters Friday with many more evacuees believed to be staying with relatives and friends.

Hawaii County officials said steam and lava poured out of a crack in the community of Leilani Estates near the town of Pahoa on the Big Island.

Footage shown on local television showed lava spurting into the sky from a crack in a road. Aerial drone footage showed a line of lava snaking through a forest.

Resident Jeremiah Osuna captured drone footage of the lava burning through the trees, a scene he described as a "curtain of fire."

"It sounded like if you were to put a bunch of rocks into a dryer and turn it on as high as you could. You could just smell sulfur and burning trees and underbrush and stuff," he told Honolulu television station KHON.

Asta Miklius, a geophysicist with the USGS Hawaiian Volcano Observatory, told The Associated Press in a phone interview that there is no way to know exactly how long the eruption will continue.

"One of the parameters is going to be whether the summit magma reservoir starts to drain in response to this event, and that has not happened yet," Miklius said. "There is quite a bit of magma in the system. It won't be just an hours-long eruption probably, but how long it will last will depend on whether the summit magma reservoir gets involved. And so we are watching that very, very closely."

County, state and federal officials had been warning residents all week that they should be prepared to evacuate, as an eruption would give little warning. Officials at the U.S. Geological Survey on Thursday raised the volcano's alert level to warning status, the highest possible, meaning a hazardous eruption is imminent, underway or suspected.

American Red Cross disaster services director Debbie Weeks said 100 people were staying in one shelter with about 20 more staying outside the shelter in their cars. Seven more people were staying at another shelter.

Henry Calio said the first sign that something might be wrong happened when he saw cracks that had emerged in the driveway of his retirement dream home in Leilani Estates. His wife Stella then received a call from an official who told them to get out immediately.

The two feared that they might lose their home.

"This is our retirement home, this is our retirement dream," Henry Calio said.

The U.S. Geological Survey said new ground cracks were reported Thursday afternoon. Hot vapor emerged from a crack and spattering lava began to erupt.

Scientists said areas downslope of the erupting vent were at risk of being covered by lava. Leilani Estates appeared to be at greatest risk, but scientists said new vents and outbreaks could occur and it's not possible to say where.

The eruption comes after days of earthquakes rattled the area's Puna district. A nearby school was closed due to the ongoing seismic activity and several roadways cracked under the strain of the constant temblors. A magnitude 5.0 earthquake was recorded hours before the eruption began Thursday.

The Puu Oo crater floor began to collapse Monday, triggering a series of earthquakes and pushing the lava into new underground chambers.

The collapse caused magma to push more than 10 miles (16 kilometers) downslope toward the populated southeast coastline of the island.

USGS geologist Janet Babb said the magma crossed under Highway 130, which leads to a popular volcano access point, on Tuesday night.

Hawaii County Civil Defense Agency closed the area to visitors on Tuesday and ordered private tour companies to stop taking people into the region.

Most of Kilauea's activity has been nonexplosive, but a 1924 eruption spewed ash and 10-ton (9-metric ton) rocks into the sky, leaving one man dead.

Puu Oo's 1983 eruption resulted in lava fountains soaring over 1,500 feet (457 meters) high. In the decades since, the lava flow has buried dozens of square miles of land and destroyed many homes.