A popular annual lambing event has been forced to shut early as fields used for parking turned into mudbaths and police were called as cars began to block a nearby road.

Lambing day at Brockhill Park School, Saltwood, is staged by the school's young farmers' club and attracts thousands of visitors. It was meant to run from 10am to 4pm today but closed at 1pm.

A bright start to the day saw 2,000 guests enjoy greeting the animals, including seeing two lambs being born this morning, browsing food stalls and taking children to a fun fair and on donkey rides.

But heavy downpours overnight turned the school's playing fields into quagmires and further heavy bursts of rain in the day saw them become more treacherous. The situation meant that only a small area of hardstanding at the school was available for parking.

When this area filled up, visitors began parking along the narrow Sandling Road, which became blocked.

Donna Ashlee, head of rural studies at the college, said: "We would normally have plenty of space to park on our playing fields but the wet weather last week and torrential rain overnight meant that cars would have got stuck on the fields, so we had to use our hardstanding area.

"When this was full up visitors began parking along Sandling Road but this was restricting access to emergency vehicles.

"It is a shame as the young people have worked so hard but safety has to come first.

"Unfortunately these things happen and we can organise everything except for the weather."

A statement from the school's vice principal Charles Joseph thanked supporters of the lambing day and praised the Brockhill young farmers who he said had made them proud.

Explaining the decision to shut the event at 1pm, he said: "So many of you came to support us and with nowhere for us to park everybody we took the decision with the police to stop selling tickets so as to avoid bringing Saltwood to a halt and inconveniencing our neighbours.

"We are really very sorry for anybody – especially the children – who may have been disappointed and hope you will be back to join us next year."