Lava flows from an erupting Hawaiian volcano have destroyed 35 buildings, officials said on Monday, as they told residents of the threatened area to be ready to "evacuate at a moment's notice" if they went to retrieve possessions from their homes.

The Hawaii Civil Defense Agency said the 1,700 people evacuated from the Leilani Estates area near the erupting Kilauea volcano on the eastern corner of the Big Island would be allowed to make brief visits back during the daylight hours on Monday, but had to be alert to the risk of deadly gas emissions.

"Be prepared to evacuate at a moment's notice," the agency said on its website. It said the Lanipuna Gardens area would be off-limits to all visitors due to deadly volcanic gases.