Prison Van Ambush in UK

The BBC has an article about a gang that ambush a prison van and released one of the passengers.  I have seen this sort of thing many times on TV and in movies but didn't realise it happened in real life as well.

The article doesn't mention how they stopped the van but

West Mercia Police said three balaclava wearing men carrying sledgehammers, smashed the windscreen and driver's window of the prison escort van.