A 7 magnitude earthquake struck Anchorage, Alaska, Friday morning, buckling roads, causing structural damage and prompting a tsunami warning that was canceled around 10 a.m. local time.

The quake struck about 10 miles north of Anchorage at 8:29 a.m. local time, according to the U.S. Geological Survey. Minutes later, a 5.8 magnitude aftershock struck.

(MORE: Major Earthquake Strikes Anchorage, Tsunami Warning Canceled)

The tremor sent employees running from office buildings and ducking under desks for cover. The Anchorage Police Department reported major infrastructure damage throughout the city in a press release, citing road and bridge closures.

Mayor Ethan Berkowitz told reporters on Friday that Anchorage, which is Alaska's most populous region, issued a civil disaster declaration to access state resources, Anchorage Daily News reported.

All flights were halted for several hours at Ted Stevens Anchorage International Airport, and some flights were rerouted to Kodiak, Fairbanks and Kenai. Major damage at Anchorage Operations Center on Ship Creek forced the closure of all Alaska Railroad operations until damage is assessed.

"It was anarchy," Brandon Slaton, a new resident of Kenai, told the Associated Press. "There's no pictures left on the walls, there's no power, there's no fish tank left. Everything that's not tied down broke."

Chugach Electric tweeted that 21,000 customers were without power on Friday afternoon, and reports of traffic lights gone dark came through as residents headed home to assess the damage. As of Friday afternoon, no casualties were reported, and it wasn't immediately clear if there were any reports of injuries.