A spokesperson for the North West Ambulance Service said nine patients were being treated.
One patient is being treated for serious injuries.
The spokesperson said: “We were called to Station Road at 2.11pm.
“We’ve attended with three ambulances, a rapid response vehicle and an advanced paramedic. There are nine patients involved altogether. It’s a collision involving a bus and a bridge.
“Three people have been taken to hospital and one person has more significant injuries.
“Richard Street and Station Street have been temporarily closed while the scene remains in place.
“No arrests have been made and enquiries are ongoing.”