(JTA) — Israeli troops killed four Palestinian gunmen and destroyed two tunnels after Palestinians set off a bomb near the Gaza-Israel border.

Five Israeli soldiers were wounded in the explosion Thursday night and one of them is in critical condition, Army Radio reported.

The gunmen were killed in retaliatory strikes by the Israel Defense Forces in the Gaza Strip, according to the report.

The charge exploded as soldiers were destroying a tunnel leading from the Gaza Strip into Israel and which the IDF say was built to facilitate terrorist attacks in Israel. The troops from the Golani infantry brigade and the Combat Engineering Corps were 300 feet into the Palestinian side of the fence when the explosion went off.

The tunnel was opposite two kibbutzim, Ein Hashlosha and Kissufim.  It was approximately 55 feet underground and one mile long, the IDF Spokesperson unit said.

In retaliatory attacks, the IDF fired a shell at terror suspects in the nearby Gazan district of Khan Younis, The Jerusalem Post reported. One Palestinian gunman was killed and a second was wounded, according to Palestinian medical sources.

Israeli air force aircraft destroyed a second tunnel in the southern Gaza Strip, the IDF stated. Three Hamas militants were killed in the strike east of the town Qarara, according to Palestinian news agency Ma’an.