The streets near Chicago Mercy Hospital in Chicago, Illinois

At least four people have died – one of them a police officer – after a gunman opened fire inside Chicago‘s Mercy Hospital.

Officers rushed to the celebrated hospital and medical centre amid reports of multiple casualties after a suspect entered the facility on the city’s South Side and started firing. It was reported the suspect, said by CNN to be a 32-year-old man, was killed in the incident, though it was not immediately clear if he had taken his own life or was shot by police. Some unconfirmed reports said his primary target was his ex-fiancee.

Anthony Guglielmi, chief communications officer for the Chicago Police Department, tweeted for people to “avoid area. Heavy police response incoming”.

A police official told NBC News that the hospital had been partially evacuated, while officers searched the premises. Some people were hiding in locked rooms. A nearby school was also placed on lockdown for a period, though students were later allowed to go home.

Mr Guglielmi named the killed Chicago police officer as Samuel Jimenez. He tweeted that "three innocent victims and the cowardly gunman who deserves to be nameless were killed tonight".

To see how events unfolded see our live coverage below

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