The mayor of Philadelphia has joined growing calls for gun control after a shootout in his city left six officers injured as they served a drug warrant.

“Our officers need help,” said Mayor Jim Kenney. “They need help with keeping these weapons out of these people’s hands.”

A gun battle broke out between police and a gunman on Wednesday, leading to a seven-hour stand-off.

The suspect reportedly carried a semi-automatic rifle and several handguns.

Mr Kenney called out politicians for their failure to address the gun crisis and confront the National Rifle Association’s powerful gun rights lobby.