A Gaza security official says two people have died in the collapse of a smugglers' tunnel under the Gaza-Egypt border and three are still trapped below ground.
The Hamas official said the tunnel collapsed while under construction.
The official said rescuers were in radio contact with the three trapped men and using bulldozers in an effort to reach them.
Dozens of tunnels run under the Gaza-Egypt border. Smugglers of fuel, weapons, drugs and other contraband have become increasingly daring since Israel and Egypt closed their borders with Gaza last year, following the violent Hamas takeover of the territory.