Beersheba, with a population of 180,000 is located 40 kilometers (18 miles) from the border with the Gaza Strip.
The Palestinian militants were using Grad missiles that have a range of approximately 40 kilometers. The missiles have the potential to reach towns home to a total of 500,000 Israelis.
"There are from six to eight people with injuries, two of whom have been sent to the hospital in a serious condition," the source said.
Over the last 20 days, three Israeli civilians and one soldier have been injured in southern Israel by rockets fired from the Hamas-controlled Gaza Strip.
One of the main reasons behind Israel's decision to launch its military offensive, now in its 20th day, was the desire to put a stop to such rocket attacks.
Since the beginning of Israel's attack on the Gaza Strip, more than 1,050 Palestinians have been killed, most of them civilians, according to the Palestinian health ministry. Around half of the dead are women, children and elderly people.
UN Secretary General Ban Ki-moon called the number of dead and injured in Gaza "unbearable," during a meeting with Israel's foreign minister on Thursday.
The UN chief's visit to Israel coincided with a large-scale military attack on Gaza City, which damaged a hospital and a UN office that coordinated efforts with Palestinian refugees. Three UN employees were injured and the office was destroyed by fire.
Thirteen Israelis have so far lost their lives in the assault, nine of whom were military personnel.