JERUSALEM (CNN) -- A rocket was fired into the Israeli coastal city of Ashkelon, Israeli police said Wednesday, but no damage or injuries were reported.
The Qassam rocket was among 20 fired from Gaza into southern Israel between Tuesday night and Wednesday morning, an Israeli police spokesman said.
Qassam rockets are simple weapons that lack guidance systems and so are very inaccurate, though in recent years militants have produced ones with longer ranges able to penetrate deeper inside Israel.
The rocket fire followed an Israeli airstrike on southern Gaza Tuesday night and clashes between Hamas militants and the Israel Defense Forces.
A total of six militants have been killed since Tuesday, Hamas security sources said Wednesday. Four were killed in the airstrike, one was killed in clashes, and one was killed when Israeli forces blew up a tunnel in Gaza, the Hamas sources said.
Palestinian sources said the Israeli airstrike happened east of the Khan Yunis refugee camp. They said a drone and an Apache helicopter could be seen.
Earlier Tuesday night, Israeli troops entered the eastern part of the Dir al-Balah refugee camp in central Gaza, Palestinian sources said.
The Israel Defense Forces said it launched a small operation Tuesday evening after its forces uncovered a tunnel "meant for the immediate abduction of IDF soldiers" about 250 meters (273 yards) from a security fence.
During the operation, the IDF said, Israeli troops exchanged fire with militants, hitting a number of them. Four Israeli soldiers suffered injuries, the IDF said.