Israeli troops and aircraft attacked Islamic militants in the southern Gaza Strip Tuesday, killing two Hamas fighters and two civilians and wounding 15 people, Hamas and Palestinian medical officials said.

Hamas said one of its men died in a pre-dawn airstrike, east of the town of Khan Younis, and a second was killed along with his 70-year-old mother when ground troops fired at their house.

An Israeli army statement said that in an operation against "terror threats" from the southern Gaza Strip, forces fired at armed militants in four separate incidents and hit the targets on each occasion.

A spokesman said aircraft carried out three attacks and ground forces shot a gunman posing a threat to soldiers.

Israeli Army Radio said troops were rounding up all local males above the age of 16 and interrogating them for information on militants.

Palestinian medical officials said a second civilian, Ibrahim al-Shami, 40, was fatally shot by soldiers when he went out onto the roof of his house and that of a total of 15 people wounded, seven were civilians.

The army often carries out raids into Gaza to target militants and to thwart rocket fire toward Israeli towns.

The military said a rocket was fired from the northern Gaza Strip toward Israel during the morning but there was no immediate report of it hitting anything.

The army also was in action Tuesday in the West Bank, where troops rounded up 13 suspects overnight and took them for questioning, an army statement said. It did not give further details.