Residents of South Korea's northwesternmost islands near the North Korean coast were evacuated to shelters on Monday as North Korea lobbed hundreds of artillery shells in their direction.
Fishermen who had gone out to sea to catch blue crab in the high season gave up midway and returned to their ports.
Around 12:20 p.m., residents were told over the public address system to make their way to the shelters.
About 3,000 of Baeknyeong's 5,562 residents, 700 of Daecheong's 1,616, and 640 of Yeonpyeong's 2,230 rushed to the nearest shelters in their neighborhood.
Schoolchildren were escorted by their teachers to the shelters in and outside their schools before they could finish their lunch.
But all were relatively calm, having been warned in the morning that the alarm could be raised after North Korea informed the South of the impending exercise.
Lee Won-mi (39), an official with the Socheong Island community service center, said, "We were worried because we heard gunfire immediately after the military announcement was made around 12:30 p.m. But there was no more gunfire after 3:30 p.m."
In the early morning, fishermen from Baeknyeong, Daecheong and Yeonpyeong islands went out in 65 fishing boats, but they had to return to nearby ports or inlets or sail into safe waters when the Incheon Coast Guard alerted them.
"A little past 1 p.m., I could hear gunfire from the North, which reminded me of the shelling of Yeonpyeong four years ago," said Kang In-koo (55), a fisherman on Yeonpyeong Island. "The blue crab season starts tomorrow, and everybody is worried if they can catch any blue crabs at all."
Ferry services between Incheon and Baeknyeong and Yeonpyeong islands were also disrupted.