No one was reported injured in the attack, Palestinian and Egyptian officials said.
But Egypt increased security in the border area after the fourth cross-border shooting since workers began building the metal barrier several weeks ago.
The construction would tighten a blockade imposed on Gaza by Egypt and Israel after the Islamic militant group Hamas seized power over the tiny coastal territory in 2007.
An Egyptian security official said nearly the full force of the 750-member border guard was called to the area, and dozens of additional armored vehicles were deployed near the frontier.
He spoke on condition of anonymity because he was not authorized to release information to reporters.
Gaza's interior minister, Fathi Hamad, said in a statement that Hamas was trying to "control" the shooting attacks.
"The government confirms that it will protect Egypt's security and it is in contact with the Egyptian government," Hamad said.
Egyptian officials have refused to confirm the barrier is being built. But in an interview published Saturday, Egyptian Foreign Minister Ahmed Aboul Gheit provided the first official confirmation that Cairo was reinforcing security along the border.
"Whether it is a wall, sensors or tapping devices ... what matters is that Egyptian territory must be protected," the weekly al-Ahram al-Arabi quoted him as saying. "Whoever says Egypt is imposing its control on the border, we tell them this is Egypt's full right."
The barrier could worsen already tense relations between Egypt and Hamas, which relies on the tunnels to skirt the blockade.
Although Egypt is worried by the presence of an Islamic militant government on its border, it has been wary about choking off the tunnel networks between Gaza and Egypt's Sinai desert.
It already has come under fire from Arab and Muslim countries for cooperating with Israel in blockading Gaza.