Two cars approached a checkpoint in a residential neighborhood of the city and two armed assailants opened fire at the policemen, the security source said.

The policemen responded, killing one of the assailants while the other fled.

The source said the attack was likely a “terrorist act,” describing it as the first of its kind in nearly three years in mainland Egypt, which has largely been spared the deadly insurgency in the Sinai peninsula.

Medical sources confirmed the casualty toll from the attack, for which there was no immediate claim of responsibility.

In the past few years, attacks against security forces have been concentrated in the restive Sinai, where extremists affiliated with ISIS continue to operate.

Eleven soldiers were killed on May 7 in an attack in western Sinai.

Days later, another five soldiers and seven extremists died when the army was attacked in the peninsula.

In February 2018, security forces launched a wide-reaching campaign seeking to root out members of extremist groups in the Sinai and elsewhere.

In May 2019, an attack near Egypt’s Giza pyramids injured 17 people, many of them foreign tourists.

And in August of that year, 20 people were killed when a car laden with explosives crashed into two other vehicles in Cairo.

Ismailia is one of the key cities overlooking Egypt’s Suez Canal, a vital waterway between Asia and Europe that sees about 10 percent of the world’s maritime trade.

The canal is a major source of foreign currency for Egypt, which is struggling with a declining currency and rising inflation.