A MYSTERY missile hurled off a motorway bridge at Eastleigh smashed the windscreen of an ambulance while it was taking a patient between hospitals.

Today police described the incident as a "stupid act" which could have led to a major accident and a fatality on one of the busiest roads in the country.

Miraculously, no one was hurt in the late afternoon drama on M3 but police were hunting the teenage thug believed to be responsible for the mindless act of vandalism.

The incident happened at about 3.30pm, just as rush hour traffic was starting to build up and it is believed to be the first time that a Hampshire ambulance has been the target of this type of vandalism.

The Southampton-based ambulance, which was not using its blue lights, had been transporting a patient from the city's General Hospital to Winchester's Royal Hampshire County Hospital.

It suddenly came under attack as it passed under a footbridge just north of the Leigh Road, Eastleigh turn-off.

As the ambulance was travelling northbound a youth in a grey sweater and trousers was seen hurling an object off the footbridge just north of the turn-off.

Neither of the two ambulance crew nor the patient were hurt. Despite the incident the ambulance was able to carry out its journey to the Winchester hospital.

The 13- to 14-year-old youth spotted on the bridge was carrying an Adidas bag.

An Eastleigh police spokesman said: "This was a very dangerous and stupid act that could have led to a serious incident on a very busy major road. Someone could have been killed."

A Hampshire Ambulance Service spokesperson said: "We are obviously very upset by the incident and it is a blessing that neither the crew nor the patient were seriously hurt.

"Obviously the implications could have been very frightening, not only for the people in the ambulance and but for other road users."

Police are appealing for anyone who might have seen the incident to contact Eastleigh traffic by ringing 08450454545.