It is unclear whether all the injured are civilians or if there are also soldiers among the wounded. For several of them, the situation is reported to be serious.
Thursday's accident occurred in Pocheon, South Korea, a town 25 kilometers south of the militarized border with North Korea, reports the South Korean news agency Yonhap.
A church building and parts of two houses were damaged, according to the state rescue service.
The South Korean air force confirms that fighter jets mistakenly dropped eight bombs outside the designated firing range during a military exercise.
"We deeply regret the unintentional release of the bombs, which resulted in civilian casualties, and wish the injured a speedy recovery," the air force says in a statement.
A local resident tells Yonhap that he was at home watching TV when the accident occurred.
I suddenly heard an enormous explosion, like thunder, and the whole house shook. When I went out, everything was chaos, he says.
The South Korean military is investigating the incident and has set up a special committee to take necessary measures, including investigating the compensation issue.
The military exercises in the area are being held together with the US military, reports Yonhap.
