An air and sea rescue was launched for a four-year-old boy who has gone missing.
The boy's parents frantically tried to rescue him after he entered the water at Burnham-on-Sea, Somerset.
A member of the public witnessed their desperate attempts and called the emergency services.
The Maritime and Coastguard Agency said a search involving a helicopter, coastguard rescue teams and two lifeboats was launched after the alarm was raised at 6.04pm on Sunday.
"The parents of the child have been treated on scene after they went in after the boy and required medical treatment for water ingestion," a spokeswoman said.
"A member of the public dialled 999 at 6.04pm to inform Swansea Coastguard that they had seen two adults go in the water to attempt to rescue a small child and that they needed medical assistance.
"Swansea Coastguard sent the Burnham-on-Sea Coastguard rescue team to the scene, along with the two Burnham-on-Sea RNLI lifeboats.
Later, Avon and Somerset Police said the search for the boy had been called off until the morning.
"A thorough search has been under way but due to loss of natural light the search has been suspended until the morning," a force spokesman added.
"The public are thanked for their assistance."