ANCHORAGE, Alaska (AP) — Back-to-back earthquakes measuring 7.0 and 5.7 shattered highways and rocked buildings Friday in Anchorage and the surrounding area, sending people running into the streets and briefly triggering a tsunami warning for islands and coastal areas south of the city.

No tsunami arrived and there were no immediate reports of deaths or serious injuries.

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, with a population of about 300,000. People ran from their offices or took cover under desks. The 5.7 aftershock arrived within minutes, followed by a series of smaller quakes.

“We just hung onto each other. You couldn’t even stand,” said Sheila Bailey, who was working at a high school cafeteria in Palmer when the quake struck. “It sounded and felt like the school was breaking apart.”

A large section of an off-ramp near the Anchorage airport collapsed, marooning a car on a narrow island of pavement surrounded by deep chasms in the concrete. Several cars crashed at a major intersection in Wasilla, north of Anchorage, during the shaking.

Anchorage Police Chief Justin Doll said he had been told that parts of Glenn Highway, a scenic route that runs northeast out of the city past farms, mountains and glaciers, had “completely disappeared.” Traffic in the three lanes heading out of the city was bumper-to-bumper and all but stopped Friday afternoon as emergency vehicles passed on the shoulder.

The quake broke store windows, knocked items off shelves, opened cracks in a two-story, downtown building, disrupted electrical service and disabled traffic lights, snarling traffic. It also threw a full-grown man out of his bathtub.

Flights at the airport were suspended for hours after the quake knocked out telephones and forced the evacuation of the control tower. And the 800-mile Alaska oil pipeline was shut down while crews were sent to inspect it for damage.

Anchorage’s school system canceled classes and asked parents to pick up their children while it examined buildings for gas leaks or other damage.

Fifteen-year-old Sadie Blake and other members of the Homer High School wrestling team were at an Anchorage school gymnasium for a tournament when the bleachers started rocking and the lights went out. People started running down the bleachers in the dark, trying to get out.

“It was a gym full of screams,” said team chaperone Ginny Grimes.

When it was over, Sadie said, there was only one thing she could do: “I started crying.”

Jonathan Lettow was waiting with his 5-year-old daughter and other children for a school bus near their home in Wasilla when the quake struck. The children got on the ground while Lettow tried to keep them calm.

“It’s one of those things where in your head, you think, ‘OK, it’s going to stop,’ and you say that to yourself so many times in your head that finally you think, ‘OK, maybe this isn’t going to stop,’” he said.

Soon after the shaking ended, the school bus pulled up and the children boarded, but the driver stopped at a bridge and refused to go across because of deep cracks in the road, Lettow said.

At Chugiak High School, acting principal Allison Susel said ceiling tiles came down, books and other items fell from shelves, and water line breaks caused damage.

Former Alaska Gov. Sarah Palin tweeted that her home was damaged: “Our family is intact — house is not. I imagine that’s the case for many, many others.” She posted a video of the inside of her parents’ home, with broken dishes littering the kitchen floor. A large set of antlers appeared to have fallen off a wall of the living room.

Gov. Bill Walker issued a disaster declaration. He was in an elevator in a high-rise Anchorage office building and said it was a “rough ride” coming down. He described the quake as a 7.2, though it was unclear why his figure differed from that of the USGS.

Walker says it will take more than a week or two to repair roads damaged by the earthquake.

“This is much more significant than that,” he told reporters at a news conference.

Walker leaves office on Monday, and he said members of Gov.-elect Mike Dunleavy’s staff had been involved with the earthquake response to ensure a smooth transition.

“This isn’t a time to do anything other than take care of Alaskans, and that’s what we’re doing,” he said.

In Kenai, southwest of Anchorage, Brandon Slaton was home alone and soaking in his bathtub when the earthquake struck. Slaton, who weighs 209 pounds, said it created a powerful back-and-forth sloshing that threw him out of the tub.

His 120-pound mastiff panicked and tried to run down the stairs, but the house was swaying so much that the dog was thrown into a wall and tumbled down the stairs, Slaton said.

Slaton ran into his son’s room after the shaking stopped. The boy’s fish was on the floor, gasping, its tank shattered. Slaton put the fish in a bowl.

“It was anarchy,” he said. “There’s no pictures left on the walls, there’s no power, there’s no fish tank left. Everything that’s not tied down is broke.”

Alaska was the site of the most powerful earthquake ever recorded in the U.S. The 9.2-magnitude quake on March 27, 1964, was centered about 75 miles (120 kilometers) east of Anchorage. It and the tsunami it triggered claimed about 130 lives.

The state averages 40,000 earthquakes a year, with more large quakes than the 49 other states combined. Southern Alaska has a high risk of earthquakes because the Earth’s plates slide past each other under the region.

Alaska has been hit by a number of powerful quakes over 7.0 in recent decades, including a 7.9 last January southeast of Kodiak Island. But it is rare for a quake this big to strike so close to such a heavily populated area.

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

“People who were outside were actively hugging each other,” he said. “You could tell that it was a bad one.”