Residents are urged to stay calm in the wake of 40 aftershocks.
People walk past a crack in the road after an earthquake near Northwoods on the Kenai Spur Highway in Kenai, Alaska Photo: AFP
The 7.0 magnitude earthquake struck just south of Point MacKenzie, Alaska, with an epicentre seven miles (11.4 km) from Anchorage, the US Geological Survey said. It had a depth of 26.7 miles (43 km).
Alaska's Governor Bill Walker has declared a state of disaster, and officials are starting to assess the damage to roads and buildings.
There are reports of building and bridge collapses, and thousands are without power, however, there are no reports of deaths or major injuries.
So far, officials have registered 40 aftershocks: many over magnitude four.
The Alaska Earthquake Centre is telling people to remain calm - saying the aftershocks are nerve-racking, but they are what they would expect for such a strong earthquake.
Earlier, the National Weather Service initially said there was no tsunami danger, but a few minutes later the agency said on Twitter that there was a warning in place for Cook Inlet, which links Anchorage with the Gulf of Alaska. It was later cancelled.
Traffic in midtown Anchorage came to a standstill after the quake and CNN reported that television station KTUU, an NBC affiliate, was knocked off the air. CBS said its affiliate KTVA was also off the air.
"Thought the house was going to come apart," Anchorage-based climatologist Brian Brettschneider wrote on Twitter, posting a picture of his kitchen floor scattered with items that had fallen from cupboards.
The quake was initially reported as having a 6.7 magnitude.
In this image courtesy of Dr Holy A Bell, books and ceiling tiles litter the floor at the Mat-Su College library in Anchorage, Alaska. Photo: AFP
Around 300,000 people live in Anchorage with 100,000 in the surrounding area.
White House press secretary Sarah Sanders tweeted that US President Donald Trump had been briefed on the quake and was "monitoring damage reports".
An earthquake of magnitude 7.0 and higher can cause, at a minimum, considerable damage in normal structures and can destroy poorly constructed structures, according to the USGS.
Officials are encouraging people to use social media and text messages to contact loved ones as phone lines may be overwhelmed.
The quake has also caused roads to break apart and other structures to collapse. Locals have also shared images of buildings on fire in the aftermath.
Air and rail travel has been disrupted by the quake as well. One of the state's largest internal airline services has suspended operations until midday.
Books and ceiling tiles litter the floor at the Mat-Su College library in Anchorage. Photo: AFP / Dr Holly A Bell
Local resident Travis Starling told the BBC there is currently no power or water and most radio stations are off air as aftershocks continue.
Mr Starling said that at this time of year, the state sees only six hours of daylight: "We're fortunate on timing... this happened just at sunrise."
"The aftershocks of the one today have been worse than any earthquake I've ever been in before," he said.
Former Alaska Governor Sarah Palin tweeted that her home was damaged in the quake.
The largest quake in US history occurred in Anchorage in 1964. The magnitude 9.2 quake was the second-largest ever measured, worldwide, and devastated the region.
Alaska has more earthquakes than any other US region and has had an average of one magnitude 7 to 8 earthquake every year since 1900, according to the state government website.
- REUTERS / BBC