North Korea went on an unexpected rampage Wednesday, launching 23 ballistic missiles and over a hundred artillery shells in the direction of South Korea.

One of the missiles came down about 35 miles from the South Korean city of Sokcho – the first time a North Korean missile has impacted south of the maritime border known as the Northern Limit Line.

South Korea’s Yonhap News reported the North Korean provocation began with three short-range ballistic missiles (SRBMs) from near the eastern coastal city of Wonsan at 8:51 a.m. local time. One of these missiles was the weapon that landed in the water near Sokcho.

More launches were detected over the next few hours, including a barrage of ten SRBMs and surface-to-air missiles fired at 9:12 a.m. The artillery barrage began around 1:27 p.m. local time. 

“Our military can never tolerate this kind of North Korea’s provocative act, and will strictly and firmly respond under close South Korea-U.S. cooperation,” the South Korean Joint Chiefs of Staff (JCS) said in a statement on Wednesday.

The JCS said North Korea’s bombardment of artillery shells into the military buffer zone between the two Koreas violated the Comprehensive Military Agreement of 2018. North Korea fired similar artillery barrages into the buffer zone in mid-October, actions denounced as “clear violations” by Seoul but billed as a “powerful military countermeasure” against U.S.-South Korean “war drills” by Pyongyang.

The JCS called the missile salvo “very unprecedented,” noting North Korea has never launched so many missiles in a single day. The missile that landed near Sokcho also threatened the island of Uleung, whose residents scrambled into shelters after air raid warnings were sounded.

After holding an emergency meeting of his National Security Council, South Korean President Yoon Suk-yeol denounced North Korea’s “act of territorial encroachment” and pledged a “swift and firm response” to ensure Pyongyang “pays the price for provocation.”

South Korean warplanes launched three precision-guided missiles into the water north of the Northern Limit Line on Wednesday in response to North Korea’s actions.

“Our military’s response reaffirms our resolve to sternly respond to any provocations, and shows that we are capable of accurately striking our enemy,” the South Korean JCS said.

The U.S. Indo-Pacific Command called North Korea’s missile launches “reckless” and “destabilizing,” and reaffirmed America’s “ironclad” commitment to defend South Korea and Japan.

South Koreans were especially outraged at the North’s actions because they are still in mourning for the deadly Halloween party stampede that killed 153 people in the Seoul entertainment district of Itaewon on Saturday night.

North Korea was once more lashing out against U.S.-South Korean military drills, in this case a five-day combined aerial exercise called Vigilant Storm that began on Monday. 

Pyongyang on Tuesday announced that such “rashness and provocation can no longer be tolerated,” and hinted it was prepared to use nuclear weapons to make America and South Korea “pay the most horrible price in history” if the drills continue.