INCHEON, South Korea — Rescuers found the burned bodies Wednesday of two islanders killed in a North Korean artillery attack — the first civilian deaths from a skirmish that marked a dramatic escalation of tensions between the rival Koreas.
The barrage on the tiny island of Yeonpyeong in the western waters near the Koreas' maritime border also killed two South Korean marines and wounded 18 others Tuesday in what U.N. Secretary-General Ban Ki-moon called one of the "gravest incidents" since the Korean War.
As South Korean troops remained on high alert and buildings continued to burn, exhausted evacuees streamed into the port city of Incheon after spending the night in underground shelters, embracing tearful family members and telling harrowing tales of destruction.
President Barack Obama underlined Washington's pledge to "stand shoulder to shoulder" with Seoul and called upon China to restrain ally North Korea.
The U.S. stations more than 28,000 troops in South Korea to guard against North Korean aggression, a legacy of the bitter three-year conflict that ended in a truce, not a peace treaty, in 1953. Seoul and Washington reaffirmed plans to stage joint military exercises later this week in the Yellow Sea, just 70 miles (110 kilometers) south of Yeonpyeong island. The White House said the USS George Washington aircraft carrier would head to Korean waters to take part.
In Pyongyang, residents boasted that the exchange showed off their military's strength and ability to counter South Korean aggression.
"I think this time our military demonstrated to the whole world that it doesn't make empty talk," Ri Pong Suk told TV news agency APTN in the North Korean capital.
China — North Korea's closet ally and its largest supplier of aid — said late Wednesday it was "highly concerned" about the exchange and urged restraint.
China "feels pain and regret about an incident causing deaths and property losses and is worried about the developments," Foreign Ministry spokesman Hong Lei said in a statement. "We have always maintained that the relevant parties should, through dialogue and consultation, resolve disputes by peaceful means."
Artillery and gunfire break out sporadically along the land and maritime borders dividing the two Koreas, and have erupted in deadly exchanges four times since 1999.
And in March, North Korea was accused of launching a torpedo that sank a South Korean warship, the Cheonan, killing 46 sailors. Seoul considers it the worst military attack on the country since the war, but Pyongyang has denied responsibility.
The North's most notorious act of terrorism was the 1987 bombing of a South Korean airliner that claimed 115 lives. And in 1996, a group of North Korean spies slipped ashore from a submarine and killed three civilians and a South Korean army private while roaming the countryside for weeks.
However, Tuesday's shower of artillery was the first to strike a civilian population. The bodies of two men, believed in their 60s, were pulled out from a destroyed construction site Wednesday, the coast guard said.
South Koreans see the killing of civilians as taking the confrontation to a new level, one analyst said.
"It's clearly a line for people, and crossing that line puts it in a different category," said John Delury, an assistant professor at Seoul's Yonsei University Graduate School of International Studies. "People here are feeling very conflicted, outrage and sorrow."
Yeonpyeong island, famous for its crabs, still looked like a war zone Wednesday, with burned-out buildings still smoldering, windows smashed and shattered, and huge craters from shells pockmarking homes, footage aired by YTN television showed.
One of the main targets was a supermarket that once housed the office of a military intelligence agency, local official Choi Chul-young told The Associated Press by telephone from the island.
It wasn't immediately clear if the North Korean military mistook the shop for the military intelligence site.
Islanders said the barrage midafternoon Tuesday took them by surprise.
"I heard the sound of artillery, and I felt that something was flying over my head," said Lim Jung-eun, 36, who fled Yeonpyeong island with three children, including a 9-month-old strapped to her back. "Then the mountain caught on fire."
About 10 homes were directly hit and 30 totally destroyed in the barrage, a local official said by telephone. She asked not to be identified. About 1,700 civilians live on Yeonpyeong in addition to troops stationed on the island just seven miles (11 kilometers) from North Korean shores.
Hundreds of island residents arrived in Incheon on rescue ships with stories of panic and chaos.
"Right after I saw the news, I called my daughter," said Chung Doo-sun, 55, who lives in nearby Gimpo city. "She was crying and told me the windows of her home were all shattered."
One 68-year-old said he still has bitter memories about the Korean War.
"North Korea has not changed at all," he said, asking to be identified only by his surname, Kim. "They are so cruel."
The chaos at the port contrasted with the calm in Seoul, the South Korean capital of more than 10 million people. Still, the skirmish weighed on people's minds.
"I never felt anxious in the past, even after the Cheonan warship incident," said Lee Ho-chul, 30. "But it feels different this time since civilians were hurt."
In Young-joo called for a strong response. "Our government has to react very strongly against North Korea after they invaded us in such a daring way," she said.
Outside Seoul's Defense Ministry, protesters stomped on photos of North Korean leader Kim Jong Il and burned his nation's flag.
South Korea said it would strengthen military forces in the western waters near Yeonpyeong and halt shipments of humanitarian aid to the communist North.
The skirmish began after North Korea warned the South to stop carrying out military drills near their sea border, South Korean officials said.
When Seoul refused and fired artillery into disputed waters — away from the North Korean shore — the North retaliated by shelling Yeonpyeong.
Seoul responded by unleashing its own barrage of K-9 155mm self-propelled howitzers and scrambling fighter jets.
Officials in Seoul said there could be considerable North Korean casualties but the exact toll wasn't clear Wednesday.
North Korea's main Rodong Sinmun newspaper published a military statement accusing South Korea of triggering the exchange, but did not mention any casualties on either side.
"The South Korean puppets should clearly know that countering the firing of the provocateurs with merciless strikes is the mode of our military's counteraction," resident Ri Myong Hun told APTN in Pyongyang.
At a military hospital in Seongnam, just outside of Seoul, relatives wailed in grief as they filed out of a memorial Wednesday for the two dead marines.
"Bring him back!" cried out Kim O-bok, 50, mother of 22-year-old marine Seo Jeong-woo, as she collapsed.Comment on this story
The deadly exchange of fire came just six weeks after North Korean leader Kim's youngest son and anointed heir, Kim Jong Un, made his international public debut by appearing at a massive military parade marking the 65th anniversary of the ruling Workers' Party.
It also came days after Pyongyang showed off its uranium enrichment facility to a visiting U.S. scientist, raising new concerns about its pursuit of atomic weapons.
The government in Pyongyang has sought to consolidate power at home ahead of a leadership transition and hopes to gain leverage abroad before re-entering international talks aimed at ending its nuclear weapons programs.
Kwang-tae Kim reported from Seoul. AP writers Ian Mader and Foster Klug in Seoul, Cara Anna in Beijing and Anne Gearan in Washington contributed to this report.