Drugs police are investigating today after stunned residents discovered a “river” of cannabis flowing down their street.

About five binbags full of the potent drug were found dumped in Poplar Crescent, Windhill, Shipley, on Wednesday night.

The large amount of cannabis leaves – believed to be worth thousands of pounds – rapidly dwindled as word spread and people flocked to the street to pick up handfuls of the drug, witnesses said.

Resident Andy Rowley found the cannabis in his street when he returned home from a family event at about 9pm.

Former prison officer Mr Rowley, who is Neighbourhood Watch co-ordinator for the area, said: “When we came home, the smell was so strong. I thought I would go and investigate with my next door neighbour.

“We were absolutely astonished – there was a river of cannabis in the street.

“Although I have been a prison officer, I have never seen raw cannabis and certainly not that much.

“There was about five binbags full. I was gobsmacked.”

Mr Rowley called the police and kept watch with other Neighbourhood Watch volunteers until they eventually arrived at about 11pm.

In that time, the cannabis had dwindled to about half its original amount as people drove by and picked it up, said Mr Rowley.

He said: “I rang up the police three times and said ‘you’ve got to get here’. They parked up and got it cleared up eventually.

“I have never seen anything like it. Even the police officer said it was the strangest call-out he had ever been on. I think the police were a bit bemused really.

“I was just glad it was gone before the kids came out for school in the morning.”

Chief Superintendent Alan Doherty, Divisional Commander of Airedale and North Bradford Police, apologised for officers not being more quickly on the scene.

He said: “Our call centre deals with far in excess of a thousand calls a day.

“On reflection, this was an incident which police should have attended more quickly and Airedale and North Bradford Police apologise for the response provided to the caller and thank him for his diligence in contacting the force.

“Inquiries are now ongoing to establish where the drugs came from and how they came to be there.”