 Police arrived at the embassy almost immediately after the first reports of gunfire, and, within ten minutes, seven DPG officers were on the scene. The officers moved to surround the embassy, but retreated when a gunman appeared at a window and threatened to open fire. Deputy Assistant Commissioner John Dellow arrived nearly 30 minutes later and took command of the operation. Dellow established a temporary headquarters in his car before moving it to the Royal School of Needlework further down Princes Gate and then to 24 Princes Gate, a nursery school. From his various command posts, Dellow coordinated the police response, including the deployment of D11, the Metropolitan Police's marksmen, and officers with specialist surveillance equipment. Police negotiators made contact with Oan via a field telephone passed through one of the embassy windows, and were assisted by a negotiator and a psychiatrist. At 15: 15 Oan issued the DRFLA's first demand, the release of 91 Arabs held in prisons in Khūzestān, and threatened to blow up the embassy and the hostages if this were not done by noon on 1 May.
