The Israeli military sounded air defence sirens near the Gaza Strip on Wednesday in what it later said was a mistake.
“This was a false alarm,” the military said on Twitter.
Israel uses sirens to warn of rocket or mortar launches by militants in Islamist Hamas-controlled Palestinian enclave.
The incident comes as Hamas and Israel considered Egyptian- and U.N.-proposed ideas for calming a more than three-month-long surge in confrontations along the Gaza border.
On Tuesday when Israel shelled a Hamas position in northern Gaza, killing two gunmen. Israel said shots had been fired at its troops from the outpost, but Hamas denied that, saying the gunmen had been taking part in shooting drill.