LUCKNOW, Sept. 6 -- Four labourers were injured when a residential boundary wall collapsed during excavation under a drain construction project in Rajajipuram D-Block on Friday afternoon. The condition of one of the four labourers trapped under the debris is critical, officials said. The drain was being constructed by AM Construction, a private firm operating under the Uttar Pradesh State Bridge Corporation. According to sources, the company allegedly has a history of safety violations but it continues to secure government contracts owing to its proximity to influential political and bureaucratic circles. Eyewitnesses and local residents alleged that excavation began without any safety precautions while approach road work for an overbridge was under way. There were no barricades, no helmets, and no structural assessments, they claimed. "They started digging without any warning, without checking if the surrounding walls were stable," said Archana Trivedi, the owner of the house whose wall collapsed. "By the time anyone could react, the wall just crumbled," she added. The injured labourers were identified as Shailesh, Shanku, Deepu and Pramod -- all from Sitapur district. Fellow workers said none of them had helmets or safety gear. "We were digging close to the wall, which suddenly gave way. Everyone got hit in the head. There was no engineer, no supervisor, just orders to dig," said a co-worker who wished not to be named. Local residents, who rescued the injured and rushed them to hospital, expressed outrage. Many pointed out that the contractor's name has figured in other mishaps across the state, yet no action has ever been taken. A senior official of the UP State Bridge Corporation said a notice had been served on AM Construction, seeking an explanation for breach of safety norms....