Grey County OPP are investigating a collision that killed a horse and injured four people.

Just after 6:30 Saturday evening, emergency crews responded to a crash between on Proton Street, Dundalk, in the Township of Southgate.

A 1997 Acura ELS was travelling north bound when it crossed over into the south bound lane, colliding head on with a south bound horse drawn buggy.

The 24 year old driver of the horse drawn vehicle, and his 39 year old passenger, both from Proton Station, were taken to hospital in Markdale.

The driver was treated and released but the passenger was transferred to LHSC in London by air ambulance with serious injuries but non-life threatening.

The 35 year old driver of the Acura, and his passenger, both from Dundalk, were also transported to the Markdale Hospital.

Eventually, the driver was transferred to the Grey Bruce Regional Health Centre in Owen Sound, with unknown injuries.

The passenger was treated and released.

Sadly, the horse died at the scene.

The investigation continues.