GAZA CITY, Palestinian Territories — Israeli soldiers and Palestinian militants traded airstrikes and rocket fire in and around Gaza on Thursday, a day after the deadliest Israeli army raid in the occupied West Bank in nearly 20 years.

Eleven Palestinians including a 16-year-old were killed and more than 80 wounded by gunfire on Wednesday, the Palestinian Health Ministry said, when Israeli troops raided the flashpoint West Bank city of Nablus, drawing international appeals for calm.

The Israeli army said it was targeting militant suspects, while top Palestinian official Hussein Al Sheikh described the raid as a "massacre" and called for "international protection for our people".

Palestinian militants hit back before dawn on Thursday, firing six rockets from Gaza into Israel. The Israeli army said it had intercepted five of them and that the sixth struck an uninhabited area.

Two hours later, the Israeli military launched airstrikes on multiple targets in Gaza, sending plumes of black smoke into the sky. The missiles targeted a weapons factory and a military camp, both run by Gaza's ruling faction Hamas, the army said in a statement.

UN Secretary General Antonio Guterres appealed for calm, warning that West Bank tensions had reached their most dangerous level in years.

"Our immediate priority must be to prevent further escalation, reduce tensions and restore calm. ...The situation in the occupied Palestinian territory is at its most combustible in years," he said, pointing to "sky high" tensions and the stalled peace process.

The Israeli army said that Wednesday's raid had targeted a hideout used by suspected militants accused of shootings in the West Bank. It said one of the wanted suspects was "neutralized" along with two others who had opened fire on troops.

Both sides exchanged fire and rockets were fired on the house by the army, spokesman Richard Hecht said.

Rocks, explosive devices, and Molotov cocktails were hurled at the troops, according to the army, which said it suffered no casualties.

The Palestinian Health Ministry said those killed in "the occupation's aggression on Nablus" were aged between 16 and 72. Hours after the raid, the ministry announced the death of a 66-year-old man from tear gas inhalation.

Since the start of this year, the Israeli-Palestinian conflict has claimed the lives of 60 Palestinian adults and children.

Israel has occupied the West Bank since the Six-Day War of 1967. Last year was the deadliest year in the territory since the United Nations started tracking casualties in 2005.

Agencies via Xinhua