A military official in Egypt says at least two troops have been killed in the collapse of a smuggling tunnel that runs along the border with the Gaza Strip.

The official said the troops had discovered the tunnel earlier Saturday and entered it to explore it. The official said one officer and a soldier were killed, while two others are still missing. He spoke on condition of anonymity because he was not authorized to speak to journalists.

Egypt's military has been sealing hundreds of smuggling tunnels under the border between Gaza and Egypt's restive Sinai Peninsula because authorities here say they are used to smuggle weapons. Islamic militants have taken refuge in Sinai, increasingly waging attacks on security forces and troops.