Israeli troops killed seven Palestinian gunmen in airstrikes in the Gaza Strip on Saturday and set up a makeshift detention center just outside the territory, part of a military offensive aimed a stopping rocket fire on Israel during the Jewish holiday of Sukkot.

On Saturday afternoon, aircraft fired three missiles at a car carrying two militants, killing at least one, Palestinian security officials said. The Israeli army said the strike targeted militants with ties to the Fatah movement of Palestinian President Mahmoud Abbas. A spokesperson said the men had launched rocket attacks at Israel.

Earlier Saturday, a missile strike killed six gunmen from the Islamic militant group Hamas, Palestinian security officials said. Fifteen people were wounded in those strikes east of Gaza City, including two who were in serious condition. A woman was also among those hurt. Witnesses said ambulances driving to the scene came under fire.

More than a dozen Israeli tanks also moved in the area, and security officials reported exchanges of fire between the Israeli forces and Palestinian gunmen.

The Israeli military said the early morning clash began when millitants fired an anti-tank missile at an Israeli bulldozer. Troops responded with fire from the air and the ground. The army confirmed that troops hit a group of Palestinian gunmen.

Saturday's deaths brought to 21 the number of Palestinians killed by Israeli troops in three days. Most of the dead were militants. However, two minors, ages 10 and 14, and 29-year-old woman were also killed.

On Friday, the army also set up a makeshift detention center next to Israel's border with Gaza to interrogate dozens of Palestinians detained in the latest incursions, an army spokeswoman said. She could not say how many Palestinians were detained so far.

Photos published by the Israeli website Ynet showed soldiers guarding a group of blindfolded, handcuffed Palestinians, their hair covered by desert dust. One soldier held up a water bottle to a detainee's mouth.

The army said troops were intensifying their offensive in areas from where militants routinely try to fire homemade rockets into southern Israel. The spokeswoman said the army hoped to prevent rocket fire during the weeklong Jewish Sukkot holiday, or Feast of Tabernacles, which ends Sunday.

Ghazi Hamad, spokesperson for the Hamas-lead government said Israel had "evil plans of a bloodly military escalation" in the Gaza Strip.

The army has carried out repeated offensives in Gaza since June 28, after militants linked to the ruling Hamas group tunneled into Israel and captured a soldier, who remains in captivity. More than 200 Palestinians have been killed since then. After a lull in the violence for several weeks, the fighting intensified in recent days.