A gun battle along Israel’s southern border with Egypt left three Israeli soldiers and an Egyptian officer dead on Saturday, officials said.

An Egyptian border guard crossed into Israel and killed the three soldiers before he was fatally shot by troops.

The Egyptian military said in a statement that he had been chasing drug smugglers when he entered Israel.

While the soldier was in pursuit of the smugglers, he breached the security checkpoint and opened fire, which led to the killing of three Israeli security personnel and the injury of two other persons, it added.

An investigation into the incident was underway, the statement said.

The Egyptian army offered its condolences to the families of the deceased and wished the injured a speedy recovery.

An Israeli source said a male and a female soldier were found dead at 8 a.m. outside their watchtower after contact was lost with them at 6 a.m.

The Israeli army said the Egyptian border guard was killed in a second exchange of fire in which the third Israeli soldier was killed.

Immediately after the incident, the Israeli army mobilized its forces and evacuated the injured to Soroka Hospital in Beersheba, southern Israel.

They also conducted a combing operation in the area in anticipation of the presence of other gunmen.

Political analyst Yoni Ben Menachem told Arab News that the Israeli-Egyptian investigation is currently focused on determining whether the Egyptian soldier was affiliated with any organization.

He said after this incident, the Israeli army would boost its military presence in the border area.

“This is an exceptional incident, but it is important to examine its motives (and) learn lessons … for the future,” Ben Menachem said.

Israel and Egypt have been at peace for over 40 years and have strong security cooperation. Fighting between the sides is extremely rare.

Lt. Col. Richard Hecht, an Israeli army spokesperson, said the fighting began overnight when soldiers thwarted a drug-smuggling attempt across the border.

Hecht said that an investigation was being conducted in full cooperation with the Egyptian army and that troops were searching for other possible assailants.

This was the first deadly exchange of fire along the Israel-Egypt border in over a decade.

It reportedly took place around the Nitzana border crossing, located about 40 km southeast of the point where Israel’s borders with Egypt and the Gaza Strip converge. It is used to import goods from Egypt destined for Israel or the Hamas-ruled Gaza Strip.

Israel built a fence along the porous border a decade ago to halt the entry of African migrants and militants who are active in Egypt’s Sinai desert.