SEOUL, South Korea (AP) — South Korea's military fired dozens of shells Thursday at rival North Korea after the North lobbed a single artillery round at a South Korean border town, the South's Defense Ministry said.

The ministry said in a statement that its artillery landed at the place where North Korea had fired its shell. There were no other immediate details from the military, but it appeared that North Korea did not respond to South Korea's returned fire.

About 80 residents in the South Korean town where the shell fell, Yeoncheon, were evacuated to underground bunkers, and authorities urged other residents to evacuate, a Yeoncheon official said, requesting anonymity because he wasn't authorized to speak to the media. He said there were no reports of injuries or damage in Yeoncheon.

In the nearby border city of Paju, residents were asked to stay home, officials said.

North Korea had previously threatened to attack South Korean loudspeakers that have been broadcasting, for the first time in 11 years, anti-Pyongyang propaganda messages across their shared border. Pyongyang also restarted its own loudspeakers aimed at the South.

The cross-border propaganda warfare followed accusations from Seoul that Pyongyang had planted land mines on the South Korean side of the Demilitarized Zone that maimed two South Korean soldiers last week.

Authoritarian North Korea is extremely sensitive to any criticism of the government run by leader Kim Jong Un, whose family has ruled since it was founded in 1948.

North Korea's army said previously in a statement that the broadcasts were a declaration of war and that if they were not immediately stopped "an all-out military action of justice" would ensue.

South Korean President Park Geun-hye urged Pyongyang to "wake up" from the delusion that it could maintain its government with provocation and threats.

Pyongyang's powerful National Defense Commission had claimed that Seoul fabricated the evidence on the land mines and demanded video proof. The land mine explosions resulted in one soldier losing both legs and another soldier one leg.