Emergergeny services have been called to help rescue a construction worker as an investigation is launched into how he became entrapped. Specialist USAR teams from the LFB have also been sent to assist at the incident following the call at around 10am on Friday to the Hammersmith Road site. Two fire engines and a fire rescue unit from Chelsea along with a command unit have also been sent  to the incident It is understood that fire crews are working with Paramedics and “HART” Teams from the London ambulance service to free the man following the collapse of a concrete staircase that has left him entrapped.   The London Fire Service and the London ambulance service have been approached for comment.   More to follow