North Korea plans to allow six detained South Koreans to return home, officials in Seoul said Thursday.

Pyongyang’s Red Cross sent a letter to the South saying the South Koreans will cross over the heavily armed border at the so-called truce village of Panmunjom on Friday, according to a short statement from the South’s Unification Ministry, which is responsible for cross-border ties.

The statement says Seoul plans to accept the South Koreans and investigate how they entered North Korea. Seoul provided only scant details, saying they were men ranging in age from 27 to 67.

North Korea said in 2010 that it was investigating four South Koreans for allegedly illegally entering the country; it wasn’t immediately clear whether any of them are among the six people being released Friday. Seoul says it has repeatedly asked Pyongyang to confirm the four citizens’ identities but has received no reply.

South Koreans visiting North Korea without government approval can be punished by up to 10 years in prison under South Korea’s National Security Law.