A Qassam rocket was fired Thursday morning at the southern industrial zone of Ashkelon and another one landed near the southern town of Sderot.
Later, a third rocket fired from the northern Gaza Strip landed near Gaza's Erez crossing.
Workers in Ashkelon reported a loud explosion and police and firefighting units were dispatched to the area in an effort to pin-point the exact landing site.
No injuries or damages were reported in the latest strikes.
The "Red Dawn" alert system that has been installed at the industrial zone was not activated this time despite pledges by security officials.
An employee of the Carlsberg plant in the area told Ynet he heard a loud explosion, followed by an announcement on the plant's public address system.
"We sat in the security rooms for about 20 minutes until they allowed us to come out," he said. "They asked us to be a bit more alert today. To our regret, we're starting to get used to this reality of Qassam attacks in this area. We also went back to work faster than before."
This is not the first time Palestinian terrorists are able to hit the industrial zone, although most of their efforts on this front fail. The last time a rocket landed in the Ashkelon area was two months ago.