JERUSALEM >> A gunbattle along Israel’s southern border with Egypt left three Israeli soldiers and an Egyptian officer dead Saturday, officials said. It was a rare instance of deadly violence along the frontier.

Israel said the Egyptian border guard crossed into Israel and killed the three soldiers before he was fatally shot by troops. Egypt said he had been chasing drug smugglers when he entered Israel.

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.

He said several hours later, two soldiers in a guard post were shot and killed. Their bodies were found after the shooting, when they did not respond to radio communications.

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

The Egyptian military said an Egyptian border guard crossed the border security barrier and exchanged fire with Israeli forces while he was chasing drug traffickers. It said in a statement that the Egyptian border guard was killed along with three Israeli troops.

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

Egypt’s Defense Minister Gen. Mohamed Zaki spoke by phone with his Israeli counterpart to discuss the shooting on the border, and “the mutual coordination to take measures to prevent such incidents in the future,” the Egyptian military said in a statement. The Egyptian minister also offered condolences for the dead Israeli troops, it said.

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

The Israeli army said one of the killed soldiers was a woman.

Criminals sometimes smuggle drugs across the border, while Islamic militant groups are also active in Egypt’s restive north Sinai.

Israel and Egypt signed a peace agreement in 1979 and maintain close security ties. Fighting along their shared border is rare.

The exchange of fire reportedly took place around the Nitzana border crossing between Israel and Egypt. The crossing is located about 40 kilometers (25 miles) southeast of the point where Israel’s border with Egypt and the Gaza Strip converge. It’s 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 Islamic militants who are active in Egypt’s Sinai desert.