Israel announced on Wednesday that it had struck Hamas “military targets” in the Gaza Strip in retaliation to a bomb attack on the border near where its troops were deployed. The army said the bomb was planted under cover of mass protests along the Gaza-Israel border since March 30. It exploded near an Israeli bulldozer on Wednesday. "During routine activity in northern Gaza, an explosive device that was placed under the guise of the riots was detonated against an (army) engineering vehicle on the western side of the security fence," a military statement said. "In response, the Israel Defense Forces struck a number of Hamas military targets," it added. No Israelis were reported injured in the explosion. There were no immediate reports on casualties from the retaliatory strikes. The statement did not give the location of the targets or the type of military fire used. Israel has used both tank fire and air strikes against Hamas targets in the past. It was also not clear what the engineering unit was working on, though Israel routinely carries out maintenance work on the border fence. Israel holds Hamas responsible for all violence emanating from Gaza and stressed that it will not allow the border area to become a combat zone. The mass rallies near the border, under the name "the Great March of Return," call for Palestinian refugees to be allowed back to their former homes now inside Israel. They have led to clashes in which Israeli forces have killed 31 Palestinians. No Israelis have been hurt.