Six Palestinians were killed and 12 others injured on Saturday in a Gaza smuggling tunnel when contraband gas canisters exploded, medics in the coastal enclave said.
The accident occurred as the canisters were being smuggled through the tunnel under the Egyptian border with the Hamas-ruled Gaza Strip, the sources said.
The impoverished territory of 1.5 million people has largely relied on the vast network of tunnels since Israel and Egypt sealed Gaza off to all but what it says is vital aid after the Islamist Hamas seized power in June 2007.
Most of the tunnels are used to bring in basic goods like food, household appliances and livestock but Hamas and other militant groups reportedly use their own more secret tunnels to bring in arms and money.
More than 130 Palestinians have died in cave-ins or been killed by Israeli military operations aimed at the tunnels since the Hamas takeover, medics say.