Gunmen killed 21 Egyptian soldiers at a security checkpoint on Saturday.
Officials said a weapons storage facility was blown up by a rocket-propelled grenade during the attack in Wadi al-Gadid governorate in western Egypt.
Security officials said the attackers were smugglers but an army spokesman said the assailants were "terrorists".
Two of the gunmen were killed in the clashes.
More top news
The veteran singer, 75, will release his 101st album - 'News of Just ... Fabulous Rock 'n' Roll' - in November.
The Duke and Duchess of Cambridge were left cautiously watching every step after making an impromptu visit aboard a steam train.
Scientists concluded 12.5% of cardiovascular deaths could be avoided if more Britons changed their diets.