One Palestinian is dead and 19 are wounded after Israeli soldiers fired on a group of Gazans who approached the border.
Farmers and young men fed up with heavily-patrolled borders and a 300 meter-wide no-entry area that includes some of their land and fields taunted the soldiers on the other side of the security fence.
The Israeli soldiers ordered them to disperse in Hebrew, then fired.
The killing comes just two days after Israel and Hamas agreed to a tenuous ceasefire, ending eight days of the fiercest rocket attacks between the Gaza Strip and Southern Israel in nearly four years.
The altercation does not seem to have endangered the ceasefire, at least not yet.
"Hamas hasn't decided to respond to the Israeli breaching of the agreement, but we hope that such violations won't be committed again," said Hamas spokesperson Sami Abu Zuhri.
In the latest tally, over 160 people are dead, nearly all of them Gazan Palestinians, more than half of whom were civilians, including 37 children. Five Israelis are among the dead.
The news of the ceasefire was met by joy and relief by both residents of Gaza and Israel, who have been hiding from the barrage of rocket attacks.
But both sides were cautious in their optimism, posturing for the sake of their constituents.
"If Israel complies, we are compliant. If it does not comply, our hands are on the trigger," said Khaled Mashal, the leader of Hamas who has been exiled to Qatar.
Israeli Prime Minister Benjamin Netanyahu spoke just as ominously.
"I know there are citizens that expected a wider military operation and it could be that it will be needed," he said. "But at this time, the right thing for the state of Israel is to take this opportunity to reach a lasting ceasefire."
No one really believes that this ceasefire will be permanent, but there are hopes that it will last longer than the previous one, in early 2009.
"This is a critical moment for the region," said U.S. Secretary of State Hillary Clinton, who cut short an Asia trip with President Obama to help broker the ceasefire at negotiations in Egypt.
"The people of this region deserve a chance to live free of fear and violence and today's agreement is a step," said Clinton.
"Now we have to focus on reaching a durable outcome. Ultimately every step must move us toward a comprehensive peace for people of the region," she said.
Rockets continued to explode minutes before the ceasefire deadline. Even after it went into effect at 9pm local time, another barrage of rockets exploded in Israel, ending only an hour after the deadline.
Gazans poured into the streets to celebrate. "God is greatest, dear people of Gaza you won," blared from loudspeakers in mosques. "You have broken the arrogance of the Jews."
In total, each side fired 1,500 rockets.
Aside from an end to open hostilities, the ceasefire agreement reopens the border crossings between the Gaza Strip and Egypt, though the Israeli blockade, which restricts the movement of people, supplies and aid into or out of Gaza, remains in place.