Bus passengers on a service into Bradford were left "shocked and shaken" after witnessing one of the "most serious" incidents of vandalism ever carried out on a First bus.

The 570 Halifax to Bradford service was on St Enoch's Road, in Wibsey, when two teenage vandals walked around the vehicle and smashed every window.

The First bus company, which operates the service, said the incident was particularly nasty and had posed serious danger to passengers.

A police spokesman said: "We received reports that two youths had smashed every window with the emergency hammer from the bus.

"There were people on the bus at the time and they were shocked and shaken, but not injured. Inquiries are continuing."

Police said the boys, one wearing a red and black hoodie and the other wearing a knitted black and white hat, are thought to have made off towards Carr Bottom Road.

They were described as white and aged between 14 and 16.

A spokesman for First said: "Vandalism to our buses is a recurring problem that we take very seriously. When people commit crime like this, they place other members of their community travelling on buses in danger.

"This is one of the most serious incidents that we have suffered, but we do suffer quite a few incidents of vandalism.

"While we are forced to spend time and money having to fix buses, it can have an impact on the service that people receive.

"We would urge anyone who knows anything to come forward and contact the police."

The incident comes just two months after young hooligans involved in a mindless wrecking spree of buses across Bradford were warned they were putting lives at risk.

The issue came to a head when more than 80 buses were damaged in just one month with one passenger injured by flying glass. The incidents prompted police and bus bosses to promise to get tough on the vandals before someone was seriously injured.

Police said school-age children had been responsible for attacks in Leeds Road, Killinghall Road, Laisterdyke, Bierley, Buttershaw and Allerton.

Anyone with information about the latest incident, which happened at about 4.15pm on Tuesday, should call Bradford South Police on 0845 6060606 or Crimestoppers on 0800 555 111.

e-mail: will.kilner @telegraphandargus.co.uk