An RAF search and rescue helicopter and three RNLI lifeboats are searching off the coast of Harwich after getting reports that two people had come off a ferry.
Then RNLI says it happened about a mile off the Harwich coast, as the ferry was heading outbound.
Also helping in the search are tug boats and other vessels that were in the area at the time.
It happened just before 10am this morning.
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Wintry showers will continue to affect East Anglia on Sunday, elsewhere it should be largely dry. Some sunny intervals are likely.
The wintry weather is continuing across the Anglia region with sleet and snow in many areas. Here is a selection of pictures from viewers.
Cold with further wintry showers which may merge into longer periods of snow after midnight.