STORY: Israel's air force hit Islamic Jihad targets in Gaza for a second day on Wednesday and Palestinian militants in the enclave began launching rockets across the border.

Sirens sounded and people - including these beachgoers in Tel Aviv - were sent running for shelter.

Esti Sherbelis lives in Tel Aviv.

"It’s frightening for both sides, it's frightening for us yes, to run to shelters. You know, I recall the past and that was terrible. And I think it’s terrible for Palestinian children who don’t have shelters as well. So I can feel for both sides and it’s a very very sad situation.”

The military said it was trying to hit rocket sites pre-emptively as blasts rocked different points including what witnesses described as a training camp in the northern part of the Gaza Strip and an open area in the south.

Several were killed, medical officials said. Their identities were not immediately clear.

Minutes after the strikes, sirens sounded in Israel -- initially among border communities but soon also in and around the commercial capital Tel Aviv, 37 miles north of Gaza.

There was no immediate word of casualties in Israel, though local media reported that a home was hit in the town of Sderot.

In Gaza, multiple contrails could be seen ascending as rockets were launched. Mid-air explosions signaled interceptions by Israel's Iron Dome aerial defense system.

On Tuesday, Israel launched a series of strikes it said were aimed at senior leaders of Islamic Jihad responsible for planning attacks against Israel. At least 10 civilians were killed in the strikes as well as three senior commanders.

There was no immediate claim of responsibility for Wednesday's rockets.

Islamic Jihad had promised to retaliate for the strikes.