The three were declared missing on Sunday night. Gaza's rescue services spokesman said that they were still alive when they found Tuesday morning but died shortly after being taken to hospital.
Earlier this month, eye witnesses reported that the Egyptian army began blocking smuggling tunnels connecting Sinai and the Gaza Strip following the terror attack that left eight Israelis dead in August. They claimed the Egyptian soldiers used various tools as well as sand and rocks to block the tunnels.
In addition, it was reported that the Egyptian army instructed locals to close the tunnels or face punishment.
Hundreds of tunnels lie beneath the Gaza-Egypt border. Some serve for the smuggling of petrol and other goods into Gaza, and others for terrorist activity.
According to the Egyptian sources, three main tunnels were traced thus far, one of which was destroyed. Previous attempts to stop the smuggling phenomenon failed. Cairo hopes that its recent plan will bring about results.
Roee Nahmias contributed to this report