The main bridge in Tadcaster has collapsed following damage caused by severe flooding in the town.
It is feared the collapse of the bridge could cause further flooding.
An Environment Agency statement read: "This severe flood warning has been issued due to the structural failure of Tadcaster Bridge over the River Wharfe in Tadcaster.
"Significant flooding is expected in the Tadcaster area.
"Those in this area are advised to evacuate immediately.
"The situation is serious and there is a significant risk to life. Please follow the advice of the emergency services and officials in the area."
Part of the ancient bridge in the centre of the town collapsed into the River Wharfe this evening after it was closed amid safety concerns.
The road was closed due to fears over the structural safety of the bridge but a small crowd gathered on Tuesday evening as stone could be heard falling into the water and creaking noises could be heard.
Just before 5pm a large chunk of the bridge fell into the water.
People watching ran as a wave headed towards the bank and a strong smell of gas came from pipes left visible in the gaping hole.
Emergency crews are at the scene.
The bridge has been closed to the public since Saturday.
More to follow.
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