Pirates seized a freighter off Somalia on Sunday, a day after a liquefied-gas tanker was commandeered near the coast of Kenya, the owners of the two vessels said.

Beluga Shipping, based in the German port-city of Bremen, said it received an emergency call during the morning from one of its vessels, the Beluga Fortune.

It said the message indicated the ship was taken over by Somali pirates, who have increased their activity in the Indian Ocean since the monsoon season ended recently.

The shipowner did not state the nationality of the crew. The vessel was on its way from the United Arab Emirates to South Africa when it was seized.

On Saturday, pirates took over the York, which was on its way from the Kenyan port of Mombasa to Mahe in the Seychelles with a cargo of liquefied natural gas.

A spokesman for the York’s Greek shipping agent said its German captain had made contact with the agent on Sunday.

“”The crew are well. I can’t say any more at the moment,”” said the spokesman, Theagenis Sarris. The tanker appeared to be moving north toward Somalia.

Sarris said the pirates had not made a ransom demand. He declined to divulge any more information, out of concern for the crew and their families.

In addition to the 68-year-old German captain, the York had a crew of 16 Filipinos and two Ukrainians.

Pirates are holding nearly 20 ships with a total of nearly 400 hostages, according to the European Union Naval Force operating off the Horn of Africa.

Most hijackings end without casualties when ransoms are paid, but often only after several months of negotiations.