A potent 7.5 magnitude earthquake rocked northern Japan late on Monday, leaving at least 23 people injured and prompting a tsunami along the Pacific coastline, according to authorities. Officials have cautioned residents about potential aftershocks and the heightened threat of a larger seismic event.

Government teams are currently assessing the damage from the tsunami and the late-night earthquake, which occurred at approximately 11:15 p.m. The epicenter was located about 80 kilometers (50 miles) off the coast of Aomori, the northernmost region of Japan’s main island, Honshu.

“I’ve never felt such intense shaking before,” said Nobuo Yamada, a convenience store owner in Hachinohe, Aomori, during an interview with NHK, Japan’s national broadcaster. He noted that, fortunately, the power supply remained intact in his area.

The Japan Meteorological Agency reported a tsunami reaching heights of up to 70 centimeters (2 feet, 4 inches) at Kuji port in Iwate prefecture, just south of Aomori. Other coastal communities in the region experienced tsunami waves up to 50 centimeters high.

The Fire and Disaster Management Agency confirmed that 23 individuals sustained injuries, including one person in serious condition. Most injuries were caused by falling objects, as reported by NHK. Among the injured were several people at a hotel in Hachinohe and a man in Tohoku who suffered minor injuries when his vehicle fell into a hole.

The meteorological agency reported the quake’s magnitude as 7.5, down from its earlier estimate of 7.6. It issued an alert for potential tsunami surges of up to 3 meters (10 feet) in some areas and later downgraded to an advisory.

Chief Cabinet Secretary Minoru Kihara urged residents to go to higher ground or seek shelter until advisories were lifted. He said about 800 homes were without electricity, and that the Shinkansen bullet trains and some local lines were suspended in parts of the region.

Nuclear power plants in the region were conducting safety checks, Kihara said. The Nuclear Regulation Authority said about 450 liters (118 gallons) of water spilled from a spent fuel cooling area at the Rokkasho fuel reprocessing plant in Aomori, but that its water level remained within the normal range and there was no safety concern.

About 480 residents were taking shelter at the Hachinohe Air Base, and 18 defense helicopters were mobilized for a damage assessment, Defense Minister Shinjiro Koizumi said.

About 200 passengers were stranded for the night at New Chitose Airport in Hokkaido, NHK reported.

The meteorological agency issued a caution about possible aftershocks in the coming days. It said there is a slight increase in risk of a magnitude 8-level quake and possible tsunami occurring along Japan’s northeastern coast from Chiba, just east of Tokyo, to Hokkaido. The agency urged residents in 182 municipalities in the area to monitor their emergency preparedness in the coming week.

Satoshi Kato, a vice principal of a public high school in Hachinohe, told NHK that he was at home when the quake struck, and that glasses and bowls fell and smashed into shards on the floor.

Kato said he drove to the school because it was designated an evacuation center, and on the way he encountered traffic jams and car accidents as panicked people tried to flee. Nobody had yet come to the school to take shelter, he said.

Prime Minister Sanae Takaichi said in brief comments to reporters that the government set up an emergency task force to urgently assess the extent of damage. “We are putting people’s lives first and doing everything we can,” she said.

Later, she urged residents in the region to pay attention to the latest information from local municipalities. “Please be prepared so you can immediately evacuate as soon as you feel a tremor.”

The quake struck about 80 kilometers (50 miles) northeast of Hachinohe, and about 50 kilometers (30 miles) below the sea surface, the meteorological agency said.

It was just north of the Japanese coast that suffered the magnitude 9.0 quake and tsunami in 2011 that killed nearly 20,000 people and destroyed the Fukushima Daiichi nuclear power plant.

“You need to prepare, assuming that a disaster like that could happen again,” the meteorological agency’s earthquake and volcano division official Satoshi Harada said.

At 6:20 a.m. on Tuesday morning, authorities lifted all tsunami advisories for the Pacific coastline in northern Japan, NHK said.

The U.S. Geological Survey reported another earthquake, with a magnitude 5.1, early on Tuesday, about 122 kilometers (76 miles) south of Honcho, at a depth of 35 kilometers. No other details were immediately available.