MILDMAY, ONT. -- An eight-year-old and a four-year-old had to be airlifted to hospital with life-threatening injuries following a horse and buggy crash near Mildmay.

In all, there were seven people in the buggy at the time of the crash, which happened around 5:40 p.m. Wednesday, just south of Mildmay, say South Bruce OPP.

A section of Bruce Road 28 from Huron-Bruce Road to Concession 2 was closed for over 10 hours as police tried to piece together what caused the crash.

Witnesses tell CTV News that the horse team ran with the damaged wagon after colliding with another vehicle. Bystanders helped catch the horses and return them to the scene.

Police are continuing their investigation and are appealing for any other witnesses to come forward with information on what may have caused the crash.

No further updates on the current condition of the children, who were taken to a London, Ont. hospital, have been released.

No other injuries have been reported and police are continuing to investigate.