Hamas arrested five people on Sunday suspected of firing a rocket into Israel.
The rocket, which was fired from Gaza on Friday, hit the Eshkol Regional Council in southern Israel, causing no damage or casualties.
Hamas officials released a statement on Sunday denying responsibility for the attack.
“Our people did not shoot the rocket and we are committed to the ceasefire,” the group said, according to Israel Radio.
Israel closed the border with Gaza for people and goods on Sunday in response to the attack. With the Gaza-Egypt border sealed following last week’s Sinai suicide attack, which killed 31 Egyptian troops, the narrow coastal strip is effectively sealed to the world.
A Hamas spokesman slammed the closing of the border.
“This is irresponsible behavior and contrary to the understandings reached at the beginning of the ceasefire,” said Moussa Abu Marzouk, the group’s Gaza spokesman.
The rocket on Friday was the second fired into Israel from Gaza since the end of Operation Protective Edge in August.