THE HAGUE, Netherlands (AP) — Dutch authorities said Tuesday that five experienced surfers drowned when they went out for a session in stormy weather off the coast of The Hague.

The group jumped into the sea late Monday and likely couldn’t deal with the combination of heavy weather, northerly winds and swells that hit the Dutch coast. An additional problem was an excessively thick layer of foam that drifted on the North Sea waters by the beaches.

Four bodies have been recovered and the Dutch coast guard said a fifth body had been seen floating in the waters while it was drifting out of reach.

The Hague mayor Johan Remkes said it was still too early to exactly say what the cause of the tragedy was, especially since the surfers had plenty of experience to assess the dangers of the waters. The age of the victims was between 22 and 38 and they lived nearby.