Police defused 18 bombs found near the main diamond markets in the city of Surat and issued a sketch of a young man believed to be linked to one of two explosives-filled cars discovered there. The announcement Tuesday came as authorities in a Mumbai suburb probed ties to a series of blasts over the weekend that killed 42 people and wounded 183 in Ahmadabad, about 280 kilometers north of Surat. An obscure Islamic militant group claimed responsibility for the Ahmadabad attack. "I request you not to go to crowded places unnecessarily," Surat Police Commissioner R.M.S. Brar told the public during a news conference, according to the Press Trust of India news agency. Authorities said four cars - two used in Saturday's Ahmadabad attack and the two found in Surat on Tuesday - were stolen in July from a Mumbai suburb, Navi Mumbai. "Once we find the people who stole the cars, it will give us further clues about the blasts," Navi Mumbai police chief Ramrao Wagh told The Associated Press.