About 400 South Koreans have crossed the heavily fortified border with the north, for a brief reunion with relatives they have not seen for more than half a century.
Their families were separated during the Korean War (1950 - 53).
The reunions are going ahead in spite of an exchange of fire on Friday, when North Korean troops fired two rounds towards a frontline unit at the border. South Korean soldiers returned fire three times.
The BBC reports the shooting occurred in Hwacheon, some 90km north-east of Seoul.
The latest reunions involve 97 South Korean families, who are meeting the same number of North Korean families at the Mount Kumgang resort on the North's southeastern coast.
A second set of reunions is set for Wednesday-Friday at the same venue, involving 96 South Koreans and 207 North Koreans.
The last reunions were held in October 2009.
Tensions between the two Koreas has been high since the South accused the North of torpedoing a warship in March, with the loss of 46 lives. Pyongyang denies the charge.
