JERUSALEM, Oct. 10 (Xinhua) -- Militants in the Gaza Strip early Wednesday fired more rockets at Israeli communities in the western Negev, as a new round of hostilities entered its fourth day.

Two Kassam rockets exploded in open areas outside the town of Sdeort, while a Grad-type rocket landed in a field in nearby Netivot, according to Israel Radio.

There were no reports of casualties or damage in either attack.

The rocket fire followed an Israel Air Force strike overnight Tuesday on an arms smuggling tunnel in northern Gaza, and other air strikes on Hamas targets in Gaza over the weekend, in which eight bystanders were injured.

The latest air strike was launched in response to more than 50 projectiles fired from Gaza in recent days, seven of them fired in the past 24 hours, the army said in a statement released late Tuesday night.

In one of the worst days of cross-border violence in weeks, the Israeli army on Monday struck targets in Gaza from the air and land, after Hamas and Islamic Jihad fired a barrage of some 55 rockets and mortar shells at farming communities in the western Negev, forcing thousands of their residents to take cover in bomb shelters and safe rooms.

On Sunday night, an Israeli air strike in Rafah killed one militant affiliated with World Jihad and critically wounded another.

The army said the two men, who were targeted while riding on a motorcycle, were in the final stages of preparing a large terror attack on Israelis, which they plotted to launch from the Egyptian Sinai.

"The Israel Defense Forces will not tolerate any attempt to harm Israeli civilians, and will operate against anyone who uses terror against the State of Israel," the army statement said.

It added that Israel holds Islamist group Hamas "solely responsible" for any militant activity emanating from Gaza.