GAZA, Feb. 11 (Xinhua) -- Two Palestinian officers were accidentally killed early Monday in a rescue mission in a tunnel dug underneath the border between Egypt and the southern Gaza Strip, a security official said.

Eyad al-Bozzom, spokesman of the Hamas-run ministry of interior, said in an e-mailed press statement that a police officer and a rescue team officer were killed overnight during a security mission of checking the underground tunnel.

The two officers died in the tunnel after inhaling toxic gases during their mission of rescuing three tunnel workers, al-Bozzom said, without revealing who sprayed the toxic gases into the tunnel.

Teams of civil defense managed to get their bodies out from the tunnel following hours of hard work, he added.

Two other security officers were rescued and taken to the hospital for medical treatment, the spokesman said.

Israel imposed a tight blockade on the Gaza Strip in 2007, right after Hamas routed the security forces of Palestinian President Mahmoud Abbas and seized control of the coastal enclave.

To overcome Israel's blockade, Hamas dug hundreds of tunnels underneath the border between southern Gaza and Egypt, which were used to bring the needed food, fuel and medicine.

However, the smuggling of goods through tunnels declined after Israel eased the blockade in 2010 and the Egyptian army destroyed more than 99 percent of the tunnels in 2015 in a large security campaign.