The mother of a Palestinian militant mourns next to his body (not seen) at the scene of an Israeli air strike in Khan Younis in the southern Gaza Strip March 12, 2012. Israeli air strikes killed two Palestinian militants and wounded 25 civilians in the Gaza Strip on Monday, medical sources said, as cross-border hostilities continued into a fourth day. [Photo/Agencies]

GAZA - Two more Palestinian fighters were killed Monday morning in separate Israeli airstrikes in the Gaza Strip, witnesses and medical sources said.

Israeli airplanes hit a three-wheeled motorcycle known as Tuk- Tuk in the southern Gaza Strip town of Khan Younis, killing an Islamic Jihad militant, witnesses said.

Another militant was wounded in the attack, in addition to a woman who was passing by the Tuk-Tuk, they added.

About an hour earlier, an Israeli surveillance drone fired a missile at a group of militants also in Khan Younis, killing an Islamic Jihad member.

The Israeli attacks, mostly directed at rocket squads and fighters, have killed 20 Palestinians, two of them being civilians, and injured 70 others since Friday, according to medical sources.

Last night alone, 33 people, including women and nine children, were injured when an Israeli missile hit a house of an Islamic Jihad member in Jabalya, the most densely populated refugee camp in the strip.

The four-day cross-border exchange of fire between Israel and Gaza militant groups has been the longest in years.

On Sunday, officials from the Popular Resistance Committee and the Islamic Jihad rejected efforts by the larger, dominant Hamas movement to restore calm. They said in statements that it was too early to discuss cease-fire, vowing to retaliate for the death of their colleagues.