FIVE people defied police and risked serious injury by leaping from Magdalen Bridge, Oxford, during Monday's May Morning celebrations.

Barriers set up at 3am and a line of 30 police and 30 private guards on either side of the crossing stopped anyone from plunging into the River Cherwell during the traditional celebrations.

But almost four hours after the security measures were lifted, the first student scaled the walls and leapt from the balustrades.

About half an hour later, four more students, all men in their 20s, jumped in one after another. One mimicked that he had hurt his leg, but none was injured.

The jumpers ignored warnings about risks of serious injury from Oxfordshire Ambulance Service, Thames Valley Police and the city and county councils, who had jointly decided to close the bridge for the first time since 2001 after more than 40 people were injured 12 seriously after leaping into the shallow river last year.

Fyn Gunn, 19, a student at Hartpury College, Gloucestershire, who regularly stays with friends in Oxford, was first to jump.

Dressed in top hat and tails, he bowed as he climbed out of the river, which is only 20 inches deep in places. The student said he was worried but "just had to jump".

Among four Oxford Brookes students who jumped were Justin Parr, 22, and Daniel Knowles, 23. Two of the group's friends were among those who jumped last year. This time, they looked on from the bridge. One said: "Our mate broke his leg last year, so we weren't going to do it again."

The authorities criticised those who jumped, but said that blocking the bridge had been a success overall.

Chief Insp Steph Cook, of Oxford police, said: "Those who jumped were irresponsible, but the main thing is that no one was injured. The whole point of closing the bridge was to stop a repeat of last year. That has worked so we are very pleased."

So few people gathered at the bridge that the county council lifted a road closure two hours earlier than the expected time of 9am. Chief Insp Cook said police took the decision to reopen the bridge after the majority of revellers had dispersed.

She said the police had to open the bridge at some point and had done all they could to prevent people from jumping.

Although the authorities were pleased that no one was injured, some people were critical of the decision to close the bridge, and during the dawn celebrations a small crowd of revellers shouted abuse at officers.

Thames Valley Police, Oxfordshire Ambulance Service, and Oxford City and Oxfordshire County Councils will meet at the end of May to discuss future closures.