Eight conspirators were arrested in a raid on June 24, 1993, after Salem had observed the group for five months. The conspirators were mixing chemicals for the bombs when they were arrested. It was revealed that the conspirators had also conducted test bombings before the World Trade Center bombing. They had also made preparations to escape quickly, which led the FBI to conclude that the suspects needed to be arrested quickly. A ninth suspect was arrested on June 30. The government announced the indictment of a tenth suspect on July 8. After the arrests were made, the Port Authority of New York and New Jersey increased security on its six river crossings between New York and New Jersey. The three crossings in the bombing plot had been under the Port Authority's purview.