Shots were fired from the Gaza Strip at a number of civilian construction vehicles just outside the Palestinian enclave on Wednesday afternoon, as Israel girded for the Hamas terrorist group to carry out a revenge attack after two of its members were killed in an IDF strike the day before.

In response, an Israeli tank shelled a Hamas observation post in the northern Gaza Strip, the army said.

There were no immediate reports of Palestinian injuries.

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The engineering vehicles that were fired upon are being used to build an underground barrier around the Gaza Strip, which is meant to counter Hamas’s network of border-crossing attack tunnels.

“Terrorists shot at civilian vehicles that were being used in the effort to construct the barrier around the security fence in the northern Gaza Strip. One vehicle was hit,” the Israel Defense Forces said.

There were no immediate reports of injuries, but the army published pictures showing damage to the vehicles. A military spokesperson said the incident was “still ongoing” so she could not comment further on the attack.

Palestinian media reported that shortly after the attack, IDF soldiers fired smoke grenades into the northern Gaza Strip, near the abandoned Karni Crossing.

It was not immediately clear if this was in response to the shooting attack or if it was an unrelated incident.

Earlier in the day, the military closed off a highway in southern Israel on Wednesday out of concerns that Hamas might open fire at Israeli vehicles.

The military said the decision to close Route 25 and several smaller service roads near the border was made in light of recent threats by Hamas and after IDF soldiers saw that the terror group had begun abandoning several of its positions in the Strip — a move Hamas generally takes as a precaution against airstrikes before carrying out attacks against Israel.

On Tuesday, an IDF tank shelled a Hamas observation post along the Gaza border, killing two of the terror group’s fighters, after soldiers nearby mistakenly believed shots had been fired at them.

The army later confirmed that the gunshots were not fired at the soldiers, but were part of a Hamas training exercise inside the Strip.

The IDF defended its decision to attack the observation post, telling the Haaretz newspaper that the shelling was justified given the information it had available at the time.

Hamas vowed to avenge its fallen members, saying it would not allow Israel to “impose a policy of bombing sites and targeting fighters without paying the price.”

According to Channel 10 news, the army conveyed messages to Hamas via Egypt acknowledging the error, but insisting that retaliatory fire on IDF troops would not be tolerated.

On Wednesday, the military said it would work to prevent any attacks against Israeli citizens by Hamas.

“The IDF will act to ensure the security of residents of the [Gaza] area and will not allow civilians and IDF soldiers to be harmed. The IDF is prepared for a variety of scenarios,” the army said Wednesday.

Earlier Wednesday, rocket sirens sounded in Israeli communities adjacent to the Gaza Strip, sending thousands of residents running to bomb shelters in what the military later said was a false alarm. The alarm systems were triggered shortly before 10 a.m. in the city of Sderot and communities in the Sha’ar Hanegev region of southern Israel.

The Israel Defense Forces did not specify what caused the false alarm. In the past, such events have been triggered by large-caliber gunfire near the border, which the military’s sensitive detection systems misidentify as rocket fire.

The flareup came amid reports that Israel and Hamas could be nearing a truce that would see a halt in the cross-border attacks and the easing of the blockade of the Strip.

Adam Rasgon and Times of Israel staff contributed to this report.