Photo: Valley Transit

A firefighter responding to a medical emergency has been killed in a shooting in Wisconsin that left three others injured, officials said.

The shooting happened after police and firefighters responded to a medical emergency around 5:30 p.m. Wednesday at Valley Transit, a bus station in downtown Appleton, fire and police officials said. Appleton Officer Meghan Cash said there was no ongoing threat to the community, but she didn't say if anyone was in custody.

A procession was held overnight in Milwaukee as the firefighter's body was brought to the Milwaukee County Medical Examiner's Office. Firefighters lined the street as emergency vehicles escorted the body. The flag-draped coffin was then brought into the medical examiner's office. The firefighter was a 14-year veteran of the Appleton Fire Department.

Fire officials say funeral arrangements for the firefighter are pending and that the investigation into the incident is ongoing.

Appleton is about 120 miles (193 kilometres) north of Milwaukee.