Several new vents opened as the volcanic eruptions continued on Friday, the County of Hawaii Civil Defense said. Authorities warned that "first responders may not be able to come to the aid of residents who refuse to evacuate," according to NBC News affiliate KHNL.

Gov. David Ige activated the Hawaii National Guard to assist with evacuations and security.

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About 770 structures are in the threatened mountainside subdivision. Government officials opened shelters at two community centers to accommodate those who rushed out of the lava's path.

There were no immediate reports of injuries, and the extent of the damage to the homes was not immediately known, Doug McCormick of Hawaii County's health and safety departments told NBC News.

High levels of "dangerous" sulfur dioxide gas was detected in the air early Friday morning. Fire officials on the Big Island said elderly residents, young people and others with respiratory issues were most susceptible to the poor air quality. A temporary flight restriction was in place for most of lower Puna.

Earlier eruptions were reported at about 4:30 p.m. Thursday (10:30 p.m. ET), about six hours after a magnitude-5.0 earthquake rattled the active Kilauea volcano following several days of smaller tremors, said the Hawaiian Volcano Observatory, an agency of the U.S. Geological Survey.