BY HORTENSE MYERS INDIANAPOLIS — ‘plc — A Marion County grand jury late Wednesday began hearing wit nesses in an effort to deter mine whether any crimes of “omission or commission” con tributed to a Halloween explo sion at the Indiana State Fair grounds in which 68 were killed. Simultaneously the Indiana State Fair Board voted to ban gas of all kinds from the 236- acre grounds and its 72 build ings. The Fair Board, at an emergency meeting Wednesday, also hired an architect, Merritt Harrison, Indianapolis, who had designed the original Coliseum, to start work on repairing the structure for opening “as soon as possible.” IN ADDITION to the grand jury probe, the major investiga tion involving city, county and state police and fire officials working in co-ordination, also continued its fact-hunting ef forts. Chief Inspector Bernard Sweeney of the Indiana fire marshal’s office told reporters after a review session Wednes day that there have been “some obvious discrepancies” in the accounts given by witnesses. “Our job is to find out who is telling the truth,” he said. Police detectives assigned to the investigation are continuing with interviews of Coliseum em ployee and others who were in jured too badly to attend a hearing held earlier at the State Office Building. Sweeney was the first witness called before the grand jury and testified for about an hour. Other witnesses called were Coliseum employee Floyd See BLAST On Page 5, Column 3