A massive sinkhole has developed in a canal in the English county of Shropshire, trapping two boats in deep mud and prompting emergency services to declare a "major incident".
An image released by Shropshire Fire and Rescue Service shows the two canal boats trapped in the sinkhole – which measures about 50 by 50 metres – while a third boat leans over the sinkhole's slope.
Canal boats are long vessels designed to navigate Britain's system of narrow canals. Historically, the boats were used to transport cargo but have since evolved into floating homes and are also used for recreational purposes.
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Rescue teams responded to a "significant breach" of the Shropshire Union Canal in Whitchurch, a historic market town about 270 kilometres north-west of London, near the Welsh border, Shropshire Fire and Rescue Service said on Monday.
A "major incident" was declared at 5.17am (6.17pm AEDT), but the situation was later declared stable, said Scott Hurford, area manager at the service. Search and rescue activity has since ended, he added.
No individuals are currently believed to be on board the affected boats and no injuries have been reported, he said.
Shropshire Fire and Rescue Service said rescue crews had been working in challenging conditions due to unstable ground and "rapidly moving water", but managed to bring more than 10 members of the public to safety. The service didn't provide further information about those people.
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Emergency services asked the public to avoid the area while teams continue to deal with the incident.
The Canal and River Trust, the largest canal charity in the United Kingdom, said on Monday that it was carrying out "initial investigations into the possible cause of the breach and will provide more details in due course".
"Our teams are on site and have dammed off the affected section of (the) canal. The priority is the safety of boaters and those in the immediate area," the charity said in a statement.