Serial sniper on the loose hunted by police after drivers targeted on Arizona's Interstate 10 motorway

At least 10 vehicles have been hit in less than two weeks along the same stretch

A bullet went through the windscreen of one of the cars hit on the Interstate 10 through Phoenix (Reuters)

Police are hunting a sniper who appears to be targeting drivers on a busy US motorway after at least 10 vehicles were shot at in less than a fortnight.

The shootings started on 29 August, when a bullet shattered the windscreen of a car travelling down the Interstate 10 highway in Phoenix, Arizona.

A 13-year-old girl sitting in the passenger seat was hurt but escaped serious injuries, authorities said.

Just half an hour later, an empty tour bus driving down the same stretch of road was struck by another bullet, which passed through its seats.

Robert McDonald, who was driving the bus at the time, told ABC News: “The person almost took me away from my family and almost caused catastrophic injuries to the other motorists on the street.”

A string of shootings on Interstate 10 highway in Phoenix prompted authorities to create a hotline to report suspicious activity or damage to vehicles (Corbis)

That night, another car was shot at and hit nearby, and other suspected shootings followed for the next two days, before resuming on Sunday, targeting vans, lorries and cars.

Tuesday saw two more shootings, including one that hit a police sergeant’s personal car, shattering his passenger window as he drove to work. He was uninjured but just 15 minutes later, a second vehicle was hit.

All of the shootings have been on the same eight-mile stretch of motorway.

Frank Milstead, director of the Arizona Department of Public Safety, told CBS News the incidents were being classed as “domestic terrorism crimes”.

The Interstate 10 passes through Phoenix, the capital of Arizona

"Anytime that you have multiple shootings against American citizens on a highway, that's terrorism,“ he said.

"They're trying to frighten or kill somebody."

Detectives are working to verify whether all cars were shot with the same weapon, or whether different projectiles were used on later days by possible copycats.

Agents with the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives have joined the investigation and drivers in the area have been warned to remain vigilant.

A $20,000 (£13,000) reward is being offered for information leading to the arrest and conviction of those responsible.