Zivile Roditis hugs Howie Rosin (L), shortly after Roditis' home was destroyed by lava from a Kilauea volcano fissure, in Leilani Estates, on Hawaii's Big Island, on May 25, 2018 in Pahoa, Hawaii.

Molten rock from several lava-spewing fissures opened by Kilauea Volcano crept toward clusters of homes and vacation rentals on the eastern tip of Hawaii's Big Island on Wednesday, prompting authorities to usher residents out of the area as a precaution.

Evacuation of the Vacationland development and adjacent Kapoho community, rebuilt after a destructive eruption of Kilauea in 1960, came on the 28th day of what geologists rank as one of the biggest upheavals in a century from one of the world's most active volcanoes.

The Hawaii County Civil Defense agency issued the advisory as lava flows picked up speed late on Tuesday and early on Wednesday and threatened to cut off a key traffic route into the seaside area on the far eastern flank of the volcano.

"Residents in the Kapoho area, including Kapoho Beach Lots and Vacationland, are advised to evacuate," the agency said in a morning bulletin. "You are at risk of being isolated due to possible lava inundation of Beach Road."

On Tuesday, a lava stream crossed a larger east-west route, Highway 132, as it advanced toward the greater Kapoho area. A separate flow of red-hot molten rock was headed in the direction of the Vacationland community to the south.

Civil defense officials also pointed to severe communication outages in the area due to downed power and phone lines, reinforcing the decision to proceed with evacuation plans immediately rather than wait for a potential emergency.

Residents were urged to stay tuned to local radio stations for further updates.

The number of people affected by Wednesday's evacuations was not precisely known, but Kapoho and Vacationland together encompass about 500 homes, mostly vacation rentals, according to Civil Defense Administrator Talmadge Magno.

An estimated 2,500 residents in all have been displaced since the eruption began nearly four weeks ago, Magno said. The bulk of evacuees were forced from their homes at the outset, in and around the Leilani Estates community farther west, where concentrations of noxious volcanic gases remain high.

Hawaii County Mayor Harry Kim on Wednesday renewed an emergency proclamation for 60 more days, allowing construction of temporary shelters and other relief projects to proceed on an expedited basis, without reviews and permits normally required.