A powerful explosion ripped through a car on a busy Gaza City beach Friday night, killed three and injuring 20, Hamas security officials said. It was the third mysterious blast of the day in Gaza after a relatively calm period that has followed a cease-fire between Israel and Hamas. No one in Gaza blamed Israel for Friday's violence and it is likely internal Palestinian battles. The late night blast killed Amar Musubah, a Hamas military field commander, Hamas member Eyad Al-Hia, a child and a fourth unknown individual. All the wounded were civilians, medical officials said.