Yemeni officials say Somali pirates have seized an empty Yemeni oil tanker in a deadly clash with coast guards. The officials said two pirates were killed in the confrontation in the Gulf of Aden Sunday. Three other pirates and two coast guards also were wounded. Earlier Sunday, Kenyan maritime groups said Somali pirates had released another Yemeni freighter and its 15 crew members. The ship was seized in January with a cargo of petroleum products.