Fire whirls are known to cause loss of lives and extreme property damages in large urban fires such as earthquake fires. This study focuses on the swirling flames generated by placing four identical symmetrical fires in a square channel with a single corner gap on one of the channel walls. The effects of the inter-fuel pan distance were examined experimentally and also numerically simulated by a field model. The numerical simulations show the existence of both the strong rotating flames and the vertical buoyant swirling flames, as also observed in the experiments. Furthermore, the simulations also show strong inflow from the channel top opening, resulting in extremely complex flow patterns inside the channel due to flow instabilities.