A search and rescue operation is under way off the coast of Essex.
Border Force and the UK Coastguard are working on the coordinated response following an incident near the port town of Harwich on Monday.
RNLI boats are also said to be in attendance.
A coastguard helicopter from Lydd has been sent to the area along with a fixed-wing aircraft.
Maritime and Coastguard Agency said in a statement: "HM Coastguard will continue to safeguard life around the seas and coastal areas of the UK, working with search and rescue resources in the area.
"If a vessel needs search and rescue assistance, HM Coastguard will continue to respond and rescue those in danger."
The RNLI has confirmed a lifeboat was launched from Harwich early Monday evening and a second was sent from another location.
A Home Office spokesman said the department would provide further details after the initial response and once the situation had been resolved.
East of England Ambulance Service has also been contacted.