Military officials inspect an area where a suspected bomb was dropped in Pocheon, Gyeonggi Province, March 6. Joint Press Corps

Pilot error is suspected to have caused an accidental fighter jet bombing of a civilian area in a border city Thursday in an unprecedented accident that left at least 15 people injured, military officials said.

Two KF-16 fighter jets "abnormally" dropped four MK-82 air-to-surface bombs each outside a training ground in Pocheon, some 40 kilometers north of Seoul, at 10:04 a.m., while taking part in joint live-fire drills with U.S. troops, according to the officials.

An Air Force official told reporters an initial investigation found that one of the pilots of the single-seat jets wrongly entered the coordinates for the strike target prior to take-off, leading to the accidental bombing.

Due to the apparent mistake, the bombs were dropped over a village about 8 kilometers away from the target at the training ground, leaving two with serious injuries and damaging eight buildings.

The official said authorities are looking into whether the pilot properly followed procedures to check the entered coordinates.

The investigation will also check for possible lapses in air traffic control as the fighter jets veered off their planned flight path due to the wrong target coordinates, according to the official.

A defense ministry official said the military will suspend all live-fire drills until the exact cause of the accident is determined.

The Air Force's top commander apologized for the accidental bombing and vowed to make the utmost effort to compensate for the damage.

"We will compensate to the full extent the mental, physical and property damage inflicted upon the residents," Air Force Chief of Staff Gen. Lee Young-su said in a statement, saying he feels a heavy responsibility for causing concern.

Lee stressed that the Air Force will thoroughly investigate the accident to hold those responsible accountable and draw up measures to prevent similar accidents going forward.

The Air Force commander said the armed forces will conduct safety education on all service members, including pilots, handling aerial armament and bolster relevant procedures.

The accidental bombing took place as South Korean and U.S. troops conducted live-fire drills, involving more than 160 pieces of military hardware, including tanks and fighter jets, at the training range near the border with North Korea.

The drills were designed to serve as a lead-up to the allies' major springtime Freedom Shield exercise scheduled to kick off Monday for an 11-day run.

A military official said Freedom Shield will take place as planned, but authorities were in talks for possible changes to on-field training. (Yonhap)