Horsham Police Leading Senior Constable Mick Ryan said the horse had bolted from the nearby Horsham Harness Racing Club.

"The horse had bolted down Bennett Road before coming to the Natimuk Road intersection," LSC Ryan said.

"The driver just clipped the horse before colliding with the other car; meanwhile, the horse ran down Natimuk Road."

LSC said the horse was safely retrieved on Natimuk Road.

A witness said they heard a car crash when they spied the runaway.

"I was standing in the kitchen when I heard a bang," they said.

"When I went outside and saw a black horse racing down the service road with another horse and jockey chasing after it."

Earlier: Motorists are being warned to drive to the conditions following an accident in Horsham on Monday, April 8.

Emergency services were called into action after 2.30pm following a two-car collision at the Natimuk and Bennett roads intersection.

Victoria Police managed traffic as Ambulance Victoria and CFA units were on hand.

The news comes just a day after a woman was airlifted to hospital and three others injured after they came off their motorbikes on the Western Freeway near Ballan.

According to Victoria Police, it was reported the four riders, in convoy, "came off their respective motorcycles on Western Freeway about 1.50pm" on Sunday, April 7.

"One of the riders was airlifted to hospital with life-threatening injuries," a police spokesperson said in a statement.

The Bureau of Meteorology issued a sheep graziers warning that cold temperatures, showers and southwesterly winds.

Areas likely to be affected include parts of the North Central, North East, Central, West and South Gippsland and East Gippsland forecast districts.