A huge concrete slab slammed to the ground in an underground parking ramp at the Olympic Stadium in Montreal Sunday afternoon, officials said. No one was hurt in the 3:20 p.m. incident, The (Montreal) Gazette reported. CTV News reported the concrete chunk, measuring 25 feet by 45 feet, fell from a ceiling section between two concrete beams at the entrance ramp of the parking lot. Firefighters examining the structure to determine the extent of the damage expressed concern that the weight of the fallen concrete could cause a secondary collapse of the ceiling of the second lot below, the network said. CJAD-AM, Montreal, reported officials said the additional weight on the first floor was making the structure unstable. \"We are already starting to see cracks in the cement,\" fire department spokesman Benoit Brouillard said. The radio station noted in 1991 a concrete slab fell off the side of the stadium itself, forcing the Montreal Expos to play their last 13 home games of the season on the road. The stadium, where the Montreal Impact professional soccer team begins play March 17, has been subject of public hearings this winter as officials scope out additional ways to utilize it. The stadium has been closed the past several winters because of concerns accumulating could cause a roof collapse.