KAILUA-KONA, Hawaii – Authorities restored electricity and began to clear away boulders Monday after the strongest earthquake to hit the Hawaiian islands in over two decades.

Twenty-four hours after Sunday’s 6.7-magnitude quake, there were no reports of any deaths or serious injuries, and there were few signs of major damage.

“It lets you know Mother Nature is doing her thing,” said Robin Eising, a teacher at Waikoloa Elementary School, which was closed for inspection. “It was a wake-up call.”

Still, officials cautioned that they were still inspecting the many bridges, roads, earthen dams, schools and other structures across the Big Island, the isle closest to the epicenter. There were no immediate estimates of the overall damage.

Utilities restored power to 97 percent of the state’s customers by early morning. That figure was expected to reach 99 percent by the end of the day. Nearly all of Oahu, the most populous island, had been blacked out on Sunday.

At least one stretch of road leading to a bridge near the epicenter collapsed, Civil Defense Agency spokesman Dave Curtis said. Several other roads on the Big Island were closed by mudslides, debris and boulders, but most were still passable, he said.

The quake hit at 7:07 a.m. Sunday, 10 miles north-northwest of Kailua-Kona, on the west coast of Hawaii Island..