Updated at 10:40 a.m. ET
South Korea and North Korea traded artillery and rocket fire on Thursday.
No one was hurt, but it was the first time tensions had escalated into an armed clash between the neighbors in five years, the New York Times reports.
Reporting for NPR from Seoul, Haeryun Kang tells Newscast that:
"South Korea's Defense Ministry says its military detected North Korea firing a single shell into Yeoncheon, a region northwest of Seoul. South Korea retaliated by firing a dozen shells back. No casualties were reported.
"Yeoncheon is evacuating more than 80 of its residents. President Park Geun-hye is holding an emergency session with the National Security Council."
At moment, there are two things heightening the conflict: The U.S. and South Korea are conducting yearly military training exercises, and the South has been blaring propaganda across the border using huge speakers.
The Times explains:
"Tensions have been on the rise along the countries' heavily armed 155-mile border since Aug. 4, when two South Korean border guards were seriously wounded by land mines that the South said were planted by the North. North Korea denied planting the mines.
"In retaliation, South Korea last week began using loudspeakers along the border to broadcast propaganda messages into North Korea, a tactic dating from the Cold War that had not been used in 11 years. The North turned on propaganda loudspeakers of its own, and it threatened to attack South Korea.
"Yeoncheon, the county where the North Korean rocket appeared to have landed, is one of the areas where the South had begun broadcasting propaganda. The South Korean military said none of its loudspeaker batteries were struck by the rocket."