A GUNMAN opened fire in a Walmart store in the Pennsylvania township of Cheltenham, prompting a massive police repsonse.

According to unconfirmed reports based on police radio scanner intercepts, emergency callers reported one ‘shooter’ and ‘multiple victims’ shortly after 6pm local time (8am AEST) .

While police are yet to confirm details, it is understood five people have been rushed to hospital with gunshot wounds after being shot at a Walmart customer service desk.

Police special weapons and tactical response (SWAT) units joined helicopters and emergency services in converging on Cedarbrook Plaza at 1000 Easton Road. The shopping centre and nearby roads were sealed off.

Local media is reporting a suspect has been detained. His vehicle had rammed a police car while apparently attempting a getaway, reports state.