This is a developing news story. Please check back for updates. (Updated at 1:48 p.m. KST on Oct. 15 with additional details throughout, correction to note that North Korea blew up roads but not railways; at 2:15 p.m. with more background; at 3:20 p.m. with expert comments; and at 4:10 p.m. with unification ministry statement)

North Korea blew up sections of two key inter-Korean roads on Tuesday, leading the South Korean military to retaliate by firing shots south of the border, according to Seoul.