Five Saudi soldiers have died on the border with Yemen, the Saudi-led coalition said late on Sunday as forces inside Yemen began a major offensive against rebels.
A coalition statement did not say how the army soldier and four Border Guard troops died in the kingdom's southern Najran region.
Neither did it specify the date of the incident.
The statement, carried by the official Saudi Press Agency, said they died "in the line of duty while protecting the nation's borders".
It appeared to be the largest single military loss in the border region announced by the coalition since March 26, when it began action in Yemen against Iran-backed Huthi rebels.
However, unlike most announcements of Saudi military casualties in the border zone, the statement gave no details.
In June the coalition said four Saudis and dozens of Yemenis were killed in battle when forces loyal to Yemen's former president attacked several locations on the Saudi border.