Gaza journalist Sami Yousef was at the beach in the north of the territory on Friday, when a series of artillery shells hit the sands, killing seven people and injuring dozens.
He recalled the day for the BBC News website.
I was just out for the day, discovering this area with a few friends, and we heard some loud explosions. As soon as we heard this we ran towards the area where the shells landed.
Many of the injured were young children on the beach for fun
We ran quickly to find out what was going on, and so I was one of the first people to arrive at the scene.
There were people lying on the ground badly injured, crying. There were remains scattered along the beach.
Three children were there, two with severe deep cuts in their heads.
One girl was just screaming, crying out for her father: 'Dad, my dad.'
It was a terrible scene, with blood everywhere. We could see a gunship in middle of sea, so we knew what had happened.
The medics arrived and started moving the bodies away. I helped them. It was shocking - it's the first time I have been around to see this kind of thing.
We took them to hospital - some to the northern Gaza hospital, some to the main hospital in Gaza City.
Nobody was expecting this to happen. Children had just finished their exams and had come with their families to the beach to enjoy the sunshine.
This was a place where people came to enjoy themselves, somewhere away from the crowds and the trouble.
A few hours later Israeli jets made sonic booms in the air over Gaza.
This was really a bad day for the Palestinians. I'm feeling sick now.
Three days of mourning have been declared for the people who died on the beach.
The beach in Gaza runs for about 40km (24 miles) and maybe people from this area won't use this section any more. But they are used to this situation, and if they feel safe they will come back.
I've heard people in the last few hours calling for revenge. If an attack happens inside Israel it will make them a little bit happy. It might also make them reject the referendum planned by [Palestinian Authority President Mahmoud] Abbas.