NEW DELHI: A day after a pedestrian causeway came crashing down at the main Games venue, leaving 27 workers injured, chunks of a false ceiling fell at the weightlifting arena of the same Jawaharlal Nehru Stadium. While the falling tiles didn't hurt anyone, the incident added to the mounting concern over India's state of readiness for the Games.Wednesday's minor disaster, however, wasn't the result of a design or construction flaw but caused by a person stepping on to a no-go zone and on the soft tiles that aren't built to take weight, officials said.But it embarrassed the organizers further as it became apparent that the culprit was likely a trespasser who may have breached the tight security each venue boasts of."A man was walking along the roof and not the catwalk, which is the way to get to the roof. When he fell, he must have grabbed on to the false ceiling, a portion of which came down along with him,'' said BK Chugh, director-general (works) of CPWD."It is an accident which should not have happened. We are taking steps to refit these tiles by tonight," said Rajendra Kala, an engineer in Chugh's department.However, neither CPWD nor Delhi Police are owning up to the trespasser getting to the roof in the first place. Asked how an unknown person could walk in and enter the roof in the face of tight security, Chugh said the matter had been referred to the cops and no one from the CPWD was involved in the incident.Delhi police said that they hadn't come across any trespasser and were checking on workers in the vicinity. "We will see images from CCTVs installed inside the hall to ascertain the identity of the trespasser. No one was injured in the mishap and no case is registered," said a senior police officer.Chugh, meanwhile, said the damage caused by the falling of the nine 2feetX2feet calcium silicate tiles was negligible. Sources said the tiles fell on the field of play area close to the VIP enclosure in the hall, which has a seating capacity of 2,500.