Ma'an News reported.
The ambulance and emergency services committee in Gaza said the three victims were found alive inside the tunnel. They were evacuated to the Abu Yousef an-Najjar Hospital in Rafah but were pronounced dead 30 minutes after arrival.
Gaza medical spokesman Adham Abu Salmiya identified the victims as Fadi Mustafa Ash-Shaer, 20, Firas Ahmad, 18, and Anwar Abu Aradeh, 25. They were all residents of al-Salam neighborhood in Rafah in southern Gaza, Abu Salmiya said.
Egyptian security officials said in early September that they were cracking down on the network of tunnels used by smugglers from the coastal enclave.
Including Tuesday's victims, eight Palestinians have been killed while working in tunnels in September. Five Palestinians were killed in three separate tunnel collapses earlier this month. Medics say over 160 Palestinians have died in the network of underground tunnels since Israel imposed a siege on the Gaza Strip in 2006.