A fragmentation grenade was thrown on Tuesday at the house belonging to Shmuel Mizrahi, the head of the Ramat Gan municipal workers union. It was the third time in two years someone has targeted Mizrahi or a family member in such a fashion.No one was hurt in the blast, which rocked the Ramat Shikma neighborhood. Light damage was caused to Mizrahi’s front yard.Police would not comment on the case, except to say it is under investigation and they have no suspects.Three weeks ago, a fragmentation grenade was thrown at the Ramat Gan home of Mizrachi’s brother, Yisrael, widely believed to be a former associate of imprisoned mob boss Ze’ev Rosenstein. No one was harmed, but the house was lightly damaged.A year and a half ago, a fragmentation grenade was also thrown at Yisrael’s house. Then, too, the grenade caused no injuries, and only slight damage to the house.A month ago, Shmuel Mizrachi led a municipal workers’ strike in Ramat Gan. During the strike a complaint was filed with police saying that he had threatened a number of workers who refused to take part in the labor action.Police are trying to determine if there is a link between the three grenade attacks and the strike. Also on Monday, Jezreel Valley police received a report that a bomb was placed outside a home in Kafr Kara, in Wadi Ara. After a brief search, police found an improvised explosive device and safely disposed of it. The investigation is ongoing.