Fifteen people were injured in South Korea on Thursday after bombs dropped by fighter jets landed in a civilian district, damaging houses and a church during military exercises in Pocheon, the Air Force and the fire department said.

The Gyeonggi-do Bukbu Fire Services said in a statement that 15 people were wounded, out of which two were seriously hurt.

Pocheon is about 40 kilometres (25 miles) northeast of Seoul, near the heavily militarised border with North Korea.

South Korea’s Air Force said eight 500-pound (225kg) Mk82 bombs from KF-16 jets fell outside the shooting range during joint live-fire exercises.

“We are sorry for the damage caused by the abnormal drop accident, and we wish the injured a speedy recovery,” the Air Force said in a statement.

Residents in the area have protested about the disturbance and potential danger from nearby training grounds for years.

Residents were evacuated around midday as authorities checked whether there were any unexploded bombs, Yonhap news agency said.

Reuters’ photographs from the scene showed shattered windows and a church building strewn with debris.

The defence ministry said earlier on Thursday that South Korea and U.S. forces were holding their first joint live-fire exercises in Pocheon, linked to annual military drills due to start next week.

South Korea and the United States will kick off their annual Freedom Shield exercise on Monday, said Seoul’s Joint Chiefs of Staff (JCS).

The joint drills, which will run until March 20, aim to strengthen the readiness of the alliance for threats such as North Korea, the JCS said.

This year’s drills will reflect “lessons learned from recent armed conflicts” and North Korea’s growing partnership with Russia, it added.

“Our planners look across the globe and identify the trends that are changing and we look at how we can incorporate that into our exercises,” Ryan Donald, a spokesperson for the United States Forces Korea (USFK), told a media briefing on Thursday.

About 70 combined field training sessions are scheduled for this year’s exercise, said Lee Sung-jun, a spokesperson for Seoul’s JCS.