Seven people were injured after shells landed on a civilian area of South Korea Thursday, according to the local broadcaster YTN.

Two shells fell on two civilian houses in the town of Pocheon, around 40 kilometers north of the capital Seoul, at about 10:00 a.m. local time (0100 GMT).

Four people were seriously wounded and three others suffered minor injuries.

According to Yonhap news agency, South Korea and the United States held a combined live-fire exercise in Pocheon, mobilizing more than 160 pieces of military hardware, such as tanks, self-propelled howitzers, helicopters and stealth jets.