An oil tanker and cargo ship are both reported to be on fire after colliding in the North Sea off the coast of Lincolnshire, the RNLI said.
The lifeboat service added that it had sent four crews to the incident this morning.
There have been reports that a number of people had abandoned the vessels following the collision, the RNLI added.
HM Coastguard sad earlier it is currently co-ordinating the emergency response around 10 miles off the coast.
The alarm was raised at just before 9.50am.
The helicopter took off from Humberside and headed to the scene alongside lifeboats from Skegness, Bridlington, Maplethorpe and Cleethorpes, and an HM Coastguard fixed wing aircraft, and nearby vessels with fire-fighting capability.
An HM Coastguard spokesperson said: "HM Coastguard is currently co-ordinating the emergency response to reports of a collision between a tanker and cargo vessel off the coast of East Yorkshire.
"The alarm was raised at 9.48am.
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