This photo provided by David Harper shows merchandise that fell off the shelves during an earthquake at a store in Anchorage, Alaska, on Friday, Nov. 30, 2018. Back-to-back earthquakes measuring 7.0 and 5.8 rocked buildings and buckled roads Friday morning in Anchorage, prompting people to run from their offices or seek shelter under office desks, while a tsunami warning had authorities urging people to seek higher ground. (David Harper via AP)

ANCHORAGE, Alaska (AP) — Back-to-back earthquakes measuring 7.0 and 5.8 rocked buildings and buckled roads Friday morning in Anchorage, prompting people to run from their offices or take cover under desks and triggering a warning to residents in Kodiak to flee to higher ground for fear of a tsunami.

The U.S. Geological Survey said the first and more powerful quake was centered about 7 miles (12 kilometers) north of Anchorage, Alaska’s largest city.

Cracks could be seen in a two-story downtown Anchorage building. It was unclear whether there were injuries.

This is what happened on the 6th floor of the Nesbett Courthouse during the Anchorage #earthquake. Both attorneys jumped under their desks. Evacuated the building after the shaking stopped. pic.twitter.com/dqHGPCv6XO

— Heather Hintze (@HeatherHintze) November 30, 2018

Photographs posted to social media sites showed damage that included collapsed ceiling tiles at an Anchorage high school and buckled roads. One image showed a car stranded on an island of pavement, surrounded by cavernous cracks where the earthquake split the road.

Cereal boxes and packages of batteries littered the floor of a grocery store, and picture frames and mirrors were knocked from living room walls.

People went back inside buildings after the first earthquake struck, but the 5.8 aftershock about five minutes later sent them running back into the streets.

Shortly after the quake, a tsunami warning was issued for the southern Alaska coastal areas of Cook’s Inlet and part of the Kenai peninsula. Kodiak police on Kodiak Island warned people in the city of 6,100 to “evacuate to higher ground immediately” because of “wave estimated 10 minutes.”

Alaska averages 40,000 earthquakes per year, with more large quakes than the 49 other states combined. Southern Alaska has a high risk of earthquakes because of tectonic plates sliding past each other under the region.

David Harper was getting some coffee at a store when the low rumble began and intensified into something that sounded “like the building was just going to fall apart.” Harper ran to the exit with other patrons there.

“The main thought that was going through my head as I was trying to get out the door was, ‘I want this to stop,'” he said. Harper said the quake was “significant enough that the people who were outside were actively hugging each other. You could tell that it was a bad one.”

On March 27, 1964, Alaska was hit by a magnitude 9.2 earthquake, the strongest recorded in U.S. history, centered about 75 miles (120 kilometers) east of Anchorage. The quake, which lasted about 4½ minutes, and the tsunami it triggered claimed about 130 lives.