Twenty people were killed, including children, and 49 were hospitalised when a railway overpass collapsed onto a busy road in Mexico City last night.<br />'' <br />''Rescue efforts for potential survivors were paused shortly after the accident, authorities said, because of the risk that more of the Metro overpass and train cars could slam down onto the road.<br />'' <br />''<span style="color: #222222;">Mexico City Mayor Claudia Sheinbaum said the rescue had been suspended because the train is very weak. A crane was being transported to the site to stabilise the train carriages so rescuers could resume their work, she said.</span><br />