JOHANNESBURG, South Africa (AFP) — A freak wave killed three swimmers and seriously injured 17 others Saturday at a popular beach in South Africa’s southeastern city of Durban, the emergency services said.

“There was a freak wave that washed some people to sea, three have drowned and 17 people have been taken to hospital,” Robert Mckenzie, spokesman of the KwaZulu-Natal provincial first responders services told AFP.

One of the dead was a child aged around seven or eight years old, and the injured are “in serious or critical condition”, he added.

But a statement from city officials said later Saturday that those killed including “a teenager”.

It said 35 lifeguards were involved in the “mass rescue effort” as paramedics attended to more than 100 people caught in the incident.

It happened at around 5:00 pm (1500 GMT) at the Bay of Plenty, one of the popular beaches in South Africa’s third-largest city.

The emergency services said that they were afraid the toll would rise.

Durban has gradually been re-opening its beaches after closure due to high levels of E.coli coming from the city’s sewer system, badly damaged by deadly floods earlier this year.

The floods, the worst in living memory, killed more than 400 people in April.