Palestinian militants fired a Russian-type Grad rocket Tuesday morning at the southern Israeli coastal city of Ashkelon.
The rocket landed in a residential neighbourhood in the city centre, "just a number of metres from heavy traffic," Mayor Beni Wakni said.
"Only Hamas has Grad rockets as far as I know, so this is Hamas," he told Israel Radio.
A military spokesman in Tel Aviv said that since Israel ended a 22-day offensive in Gaza aimed at curbing such rocket attacks from the strip, militants there had fired nearly 40 rockets at southern Israel, reported dpa.
Most of them are locally produced rockets that have a smaller range than the Grad.
Israel has responded with sporadic airstrikes, killing one Palestinian Monday in an attack on a vehicle in the southern Gaza town of Rafah and attacking tunnels along the border with Egypt late Sunday.
The attacks come as Hamas officials were in Cairo, debating with Egyptian officials a long-term truce with Israel.