Five Palestinians were killed on Friday night when a tunnel under the border between Egypt and the Gaza Strip collapsed, a Palestinian official said.
"At least five Palestinians have been killed and 15 more were injured" in the accident near Rafah, said the area's emergency services director Mohahya Hassine.
"The accident was perhaps caused by a gas explosion," Hassine added.
An Israeli blockade of the poverty-stricken Palestinian territory has been in force since Hamas seized control last year from forces loyal to secular Palestinian president Mahmud Abbas.
The border town of Rafah has frequently been used as a crossing point for arms and explosives trafficked through underground tunnels, according to Israel.