The lava flow from the Kilauea volcano has been slogging toward the village of Pahoa for weeks and was clocked at average speeds of 10 to 15m an hour as it bubbled over a road and overran a cemetery.
As of Wednesday morning (local time), the Hawaii Civil Defense agency reported the lava had advanced to within 280m of Pahoa Village Road, the main street through the town of about 800 residents. Pahoa's business district lies mostly to the south of the area in greatest danger.
On Tuesday the molten rock topping temperatures of 900degC engulfed a utility shed but spared the adjacent rental house on the property, already evacuated and cleared of furniture and other belongings, civil defense director Darryl Oliveira said.
Late Tuesday, a finger of lava had oozed back in the direction of the abandoned home, while the main flow was expected to gain momentum on the steepening slope closer to shore.
Officials said they would close an endangered elementary school on Wednesday and shutter four more schools on Thursday.
The US Geological Survey's Hawaiian Volcano Observatory said the leading edge of the lava stream had narrowed to about 55m across.
Residents of about 50 homes in its projected path were urged to prepare to leave, and many have slowly emptied their houses.
"Today it's sad and anxious. It just kind of hurts right in your stomach," said Paula Modjeska, a healthcare worker who has lived in the town for 40 years. "I just always thought Pahoa would be here."
Kilauea's current eruption began in 1983, and the fresh activity stems from a June 27 flow from its Pu'u O'o vent. That flow came to a standstill in September before resuming several weeks ago. It has crossed a road, overrun a cemetery and triggered methane explosions.
Crews have been building temporary access roads and trying to protect Highway 130, the principal route into the area travelled by as many as 10,000 cars a day.
Lava from Kilauea destroyed more than 180 homes between 1983 and 1990, but until now none since 2012.
