Palestinian witnesses say an angry crowd of people in the Gaza Strip has stormed a border crossing with Egypt and is throwing rocks at Egyptian troops.
The witnesses say Egypt is repelling the crowd with water cannons, and no one has made it across the border.
The Palestinians are upset that they are not being allowed to cross into Egypt. The Egyptians had promised to open the Rafah crossing on Tuesday, but only a small number of Palestinians have been allowed through.
Egypt has kept the crossing sealed since Hamas militants seized control of Gaza more than a year ago.
Rafah is the main gateway for Palestinians to the outside world. In January, Hamas operatives blew open the border, allowing thousands of people to cross through until it was resealed about two weeks later.