Rescue ships and aircraft participating in the search were unable to locate the four missing crew members on Tuesday, and divers sent down to the wreck of the Verity to check for any signs of life did not find anything.

Officials said that the water temperature at the time of the collision was about 12 degrees Celsius (54 degrees Fahrenheit), which experience shows most people can survive for about 20 hours.

Germany’s Central Command for Maritime Emergencies said the entire sea area where the missing sailors might be was searched again during the night without success, and rescuers then stopped the search.

A diving robot was sent down Wednesday to take another look at the wreckage but didn’t find any people, German news agency dpa reported. The head of the emergency command, Robby Renner, said hours later that there was no longer any hope for the missing.

The larger cargo ship involved in the collision — the Bahamas-flagged Polesie, which had 22 people on board — was able to reach the German port of Cuxhaven under its own steam.

There has been no word on the cause of the collision. Germany’s Federal Bureau of Maritime Casualty Investigation said it was investigating along with counterparts from the two ships’ flag states.